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Plant sexuality

January 11, 2012 at 7:27 pm (Sicence)

Close-up of an Echinopsis spachiana flower, showing both carpels (only the styles and stigmas are visible) and stamens, making it a perfect flower.

Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants.

Among all living organisms, flowers, which are the reproductive structures of angiosperms, are the most varied physically and show the greatest diversity in methods of reproduction of all biological systems.[1] Carolus Linnaeus (1735 and 1753) proposed a system of classification of flowering plants based on plant structures, since plants employ many different morphological adaptations involving sexual reproduction, flowers played an important role in that classification system. Later on Christian Konrad Sprengel (1793) studied plant sexuality and called it the “revealed secret of nature” and for the first time it was understood that the pollination process involved both biotic and abiotic interactions (Charles Darwin‘s theories of natural selection utilized this work to promote his idea of evolution). Plants that are not flowering plants (green alga, mosses, liverworts, hornworts, ferns and gymnosperms such as conifers) also have complex interplays between morphological adaptation and environmental factors in their sexual reproduction. The breeding system, or how the sperm from one plant fertilizes the ovum of another, is the single most important determinant of the mating structure of nonclonal plant populations. The mating structure or morphology of the flower parts and their arrangement on the plant in turn controls the amount and distribution of genetic variation, a central element in the evolutionary process.[2]

Terminology

The flowers of angiosperms are determinate shoots that have sporophylls. The parts of flowers are named by scientists and show great variation in shape, these flower parts include sepals, petals, stamens and carpels. As a group the sepals form the calyx and as a group the petals form the corolla, together the corolla and the calyx is called the perianth. In flowers which possess indistinguishable calyx and corolla, the individual units are then called “tepals”. The stamens collectively are called the androecium and the carpels collectively are called the gynoecium.

The complexity of the systems and devices used by plants to achieve sexual reproduction has resulted in botanists and evolutionary biologists using numerous terms to describe physical structures and functional strategies. Dellaporta and Calderon-Urrea (1993) list and define a variety of terms used to describe the modes of sexuality at different levels in flowering plants. This list is reproduced here,[3] generalized to fit more than just plants that have flowers, and expanded to include other terms and more complete definitions.

 

The Alder is monoecious. Shown here: maturing male flower catkins on right, last year’s female catkins on left

 

Individual reproductive unit (a flower in angiosperms)

• Bisexual or perfect flowers have both male (androecium) and female (gynoecium) reproductive structures, including stamens, carpels, and an ovary. Flowers that contain both androecium and gynoecium are called androgynous or hermaphroditic. Examples of plants with perfect or bisexual flowers include the lily, rose, and most plants with large showy flowers, though a perfect flower does not have to have petals or sepals. Other terms widely used are monoclinous, and synoecious. A complete flower is a perfect flower with petals and sepals.
• Unisexual: Reproductive structure that is either functionally male or functionally female. In angiosperms this condition is also called diclinous, imperfect, or incomplete.

 

Individual plant sexuality

Many plants have complete flowers that have both male and female parts, others only have male or female parts and still other plants have flowers on the same plant that are a mix of male and female flowers. Some plants even have mixes that include all three types of flowers, where some flowers are only male, some are only female and some are both male and female. A distinction needs to be made between arrangements of sexual parts and the expression of sexuality in single plants versus the larger plant population. Some plants also undergo what is called Sex-switching, like Arisaema triphyllum which express sexual differences at different stages of growth. In some arums smaller plants produce all or mostly male flowers and as plants grow larger over the years the male flowers are replaced by more female flowers on the same plant. Arisaema triphyllum thus covers a multitude of sexual conditions in its lifetime; from nonsexual juvenile plants to young plants that are all male, as plants grow larger they have a mix of both male and female flowers, to large plants that have mostly female flowers.[4] Other plant populations have plants that produce more male flowers early in the year and as plants bloom later in the growing season they produce more female flowers. In plants like Thalictrum dioicum all the plants in the species are either male or female.

Specific terms are used to describe the sexual expression of individual plants within a population.

• Hermaphrodite, a plant that has only bisexual reproductive units (flowers, conifer cones, or functionally equivalent structures). In angiosperm terminology a synonym is monoclinous from the Greek “one bed”.
• Monoecious, an individual that has both male and female reproductive units (flowers, conifer cones, or functionally equivalent structures) on the same plant; from Greek for “one household”. Individuals bearing separate flowers of both sexes at the same time are called simultaneously or synchronously monoecious. Individuals that bear flowers of one sex at one time are called consecutively monoecious; plants may first have single sexed flowers and then later have flowers of the other sex. Protoandrous describes individuals that function first as males and then change to females; protogynous describes individuals that function first as females and then change to males.
• Dioecious refers to a plant population having separate male and female plants. That is, no individual plant of the population produces both microgametophytes (pollen) and megagametophytes (ovules); individual plants are either male or female.[5] From Greek for “two households”. [Individual plants are not called dioecious; they are either gynoecious (female plants) or androecious (male plants).]

• Androecious, plants producing male flowers only, produce pollen but no seeds, the male plants of a dioecious population.
• Gynoecious, plants producing female flowers only, produces seeds but no pollen, the female of a dioecious population. In some plant populations, all individuals are gynoecious with non sexual reproduction used to produce the next generation.

• Subdioecious, a tendency in some dioecious populations to produce monoecious plants. The population produces normally male or female plants but some are hermaphroditic, with female plants producing some male or hermaphroditic flowers or vice versa. The condition is thought to represent a transition between hermaphroditism and dioecy.[6]

• Gynomonoecious has both hermaphrodite and female structures.
• Andromonoecious has both hermaphrodite and male structures.
• Subandroecious has mostly male flowers, with a few female or hermaphrodite flowers.
• Subgynoecious has mostly female flowers, with a few male or hermaphrodite flowers.

• Polygamy, plants with male, female, and perfect (hermaphrodite) flowers on the same plant, called trimonoecious or polygamomonoecious plants, (see next section for use for plant populations).[7] A polygamous inflorescence has both unisexual and bisexual flowers.[8]

• Trimonoecious (polygamous) – male, female, and hermaphrodite floral morphs all appear on the same plant.

• Diclinous (“two beds”), an angiosperm term, includes all species with unisexual flowers, although particularly those with only unisexual flowers, i.e. the monoecious and dioecious species.

 

Holly (Ilex aquifolium) is dioecious: (above) shoot with flowers from male plant; (top right) male flower enlarged, showing stamens with pollen and reduced, sterile stigma; (below) shoot with flowers from female plant; (lower right) female flower enlarged, showing stigma and reduced, sterile stamens with no pollen

Plant population

Most often plants show uniform sexual expression in populations or species wide and specific terms are used to describe the sexual expression of the population or species.

• Hermaphrodite, plants whose flowers have both male and female parts.
• Monoecious (meaning “one house” in Greek) plants have separate male and female flowers on the same plant. A plant population where the male and female organs are found in different flowers on the same plant. These plants are often wind pollinated. Examples of monoecious plants include corn,[9] birch and pine trees,[10] and most fig species.[11]
• Dioecious (meaning “two houses” in Greek), all plants are either female or male. The American Holly (Ilex opaca) is a famous example.
• Androdioecious, both male and hermaphrodite plants present.

• Gynodioecious, both female and hermaphrodite plants present. In some plants, strictly female plants are produced by the degeneration of the tapetum, a shell-like structure in the anther of a flower where the pollen cells form,[12]

• Gynoecy plants are all females in a population, often regulated by environmental factors like temperature, photo period or water availability.
• Polygamous, when there is a mix of hermaphrodite and unisexual plants in the natural population.[13]

• Subdioecious, population of unisexual (dioecious) plants, with monoecious individuals too.[14]
• Trioecious, sometimes used in place of subdioecious when male, female, and hermaphrodite plants are more equally mixed within the same population.

• Polygamodioecious, having bisexual and male flowers on some plants, and bisexual and female flowers on others.[15]

About 11% of all angiosperms are strictly dioecious or monoecious. Intermediate forms of sexual dimorphism, including gynodioecy and androdioecy, represent 7% of the species examined of a survey of 120,000 plant species. In the same survey, 10% of the species contain both unisexual and bisexual flowers.[16]

The majority of plant species use allogamy, also called cross-pollination, as a means of breeding. Many plants are self-fertile and the male parts can pollinate the female parts of the same flower and/or same plant. Some plants use a method known as self-incompatibility to promote outcrossing. In these plants, the male organs cannot fertilize the female parts of the same plant; other plants produce male and female flowers at different times to promote outcrossing.

Dichogamy is common in flowering plants, and occurs when bisexual (perfect) flowers (or sometimes entire plants) produce pollen when the stigmas of the same flower is not receptive of the pollen. This promotes outcrossing by limiting what is called autopollination or self pollination or selfing.[17] These plants are called dichogamous. Some plants have bisexual flowers but the pollen is produced before the stigma of the same flower is receptive of pollen, these are described as protandrous flowers; in a similar way, protogyny describes flowers that have stigmas that can accept pollen before the same flower or plant sheds its pollen.[7]

Flower morphology

A species such as the ash tree (Fraxinus excelsior L.), demonstrates the possible range of variation in morphology and functionality exhibited by flowers with respect to gender. Flowers of the ash are wind-pollinated and lack petals and sepals. Structurally, the flowers may be either male or female, or even hermaphroditic, consisting of two anthers and an ovary. A male flower can be morphologically male or hermaphroditic, with anthers and a rudimentary gynoecium. Ash flowers can also be morphologically female, or hermaphroditic and functionally female.

The Asteraceae or sunflower family with close to 22,000 species,[18] have highly modified inflorescences that are flowers collected together in heads composed of a composite of individual flowers called florets. Heads with florets of one sex, when the flowers are pistillate or functionally staminate, or made up of all bisexual florets, are called homogamous and can include discoid and liguliflorous type heads. Some radiate heads may be homogamous too. Plants with heads that have florets of two or more sexual forms are called heterogamous and include radiate and disciform head forms, though some radiate heads may be heterogamous too.

Evolution

Angiosperms

It is thought that flowering plants evolved from a common hermaphrodite ancestor, and that dioecy evolved from hermaphroditism. Hermaphroditism is very common in flowering plants; over 85% are hermaphroditic, whereas only about 6-7% are dioecious and 5-6% are monoecious.[19][20]

A fair degree of correlation (though far from complete) exists between dioecy/sub-dioecy and plants that have seeds dispersed by birds (both nuts and berries). It is hypothesized that the concentration of fruit in half of the plants increases dispersal efficiency; female plants can produce a higher density of fruit as they do not expend resources on pollen production, and the dispersal agents (birds) need not waste time looking for fruit on male plants. Other correlations with dioecy include: tropical distribution, woody growth form, perenniality, fleshy fruits, and small, green flowers.[21]

Plant growth regulators can be used to alter flower and plant sexuality, in cucumbers ethephon is used to delay staminate flowering and transforms monoecious lines into all-pistillate or female lines. Gibberellins also increase maleness in cucumbers. Cytokinins have been used in grapes that have undeveloped pistils to produce functional female organs and seed formation.

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Homosexual behavior due to genetics and environmental factors

January 11, 2012 at 7:23 pm (Sicence)

Published: Saturday, June 28, 2008 – 17:21 in Psychology & Sociology

Homosexual behaviour is largely shaped by genetics and random environmental factors, according to findings from the world’s largest study of twins. Writing in the scientific journal Archives of Sexual Behavior, researchers from Queen Mary’s School of Biological and Chemical Sciences, and Karolinska Institutet in Stockholm report that genetics and environmental factors (which are specific to an individual, and may include biological processes such as different hormone exposure in the womb), are important determinants of homosexual behaviour.

Dr Qazi Rahman, study co-author and a leading scientist on human sexual orientation, explains: “This study puts cold water on any concerns that we are looking for a single ‘gay gene’ or a single environmental variable which could be used to ‘select out’ homosexuality – the factors which influence sexual orientation are complex. And we are not simply talking about homosexuality here – heterosexual behaviour is also influenced by a mixture of genetic and environmental factors.

The team led by Dr Niklas Långström at Karolinska Institutet conducted the first truly population-based survey of all adult (20-47 years old) twins in Sweden. Studies of identical twins and non-identical, or fraternal, twins are often used to untangle the genetic and environmental factors responsible for a trait. While identical twins share all of their genes and their entire environment, fraternal twins share only half of their genes and their entire environment. Therefore, greater similarity in a trait between identical twins compared to fraternal twins shows that genetic factors are partly responsible for the trait.

This study looked at 3,826 same-gender twin pairs (7,652 individuals), who were asked about the total numbers of opposite sex and same sex partners they had ever had. The findings showed that 35 per cent of the differences between men in same-sex behaviour (that is, that some men have no same sex partners, and some have one or more) is accounted for by genetics. Rahman explains:

“Overall, genetics accounted for around 35 per cent of the differences between men in homosexual behaviour and other individual-specific environmental factors (that is, not societal attitudes, family or parenting which are shared by twins) accounted for around 64 per cent. In other words, men become gay or straight because of different developmental pathways, not just one pathway.”

For women, genetics explained roughly 18 per cent of the variation in same-sex behaviour, non-shared environment roughly 64 per cent and shared factors, or the family environment, explained 16 per cent.

The study shows that genetic influences are important but modest, and that non-shared environmental factors, which may include factors operating during foetal development, dominate. Importantly, heredity had roughly the same influence as shared environmental factors in women, whereas the latter had no impact on sexual behaviour in men.

Dr Rahman adds: “The study is not without its limitations – we used a behavioural measure of sexual orientation which might be ok to use for men (men’s psychological orientation, sexual behaviour, and sexual responses are highly related) but less so for women (who show a clearer separation between these elements of sexuality). Despite this, our study provides the most unbiased estimates presented so far of genetic and non-genetic contributions to sexual orientation.”

ref: http://esciencenews.com/articles/2008/06/28/homosexual.behavior.due.genetics.and.environmental.factors

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Homosexuality and Biology

January 11, 2012 at 6:50 pm (Sicence)

By CHANDLER BURR

The issue of homosexuality has arrived at the forefront of America’s political consciousness. The nation is embroiled in debate over the acceptance of openly gay soldiers in the U.S. military. It confronts a growing number of cases in the courts over the legal rights of gay people with respect to marriage, adoption, insurance, and inheritance. It has seen referenda opposing gay rights reach the ballot in two states and become enacted in one of them—Colorado, where local ordinances banning discrimination against homosexuals were repealed. The issue of homosexuality has always been volatile, and it is sure to continue to inflame political passions.

It is timely and appropriate that at this juncture a scientific discipline, biology, has begun to ask the fundamental question What is homosexuality? And it has begun to provide glimmers of answers that may in turn not only enhance our self-knowledge as human beings but also have some influence, however indirect, on our politics.

What makes the science in this case so problematic, quite apart from the usual technical difficulties inherent in biological research—particularly neurobiological research, which accounts for much of the present investigation—is the ineffable nature of our psychosexual selves.

This encompasses a vast universe of stimulation and response, of aesthetic and erotic sensibilities. There are those who see an element of hubris in the quest to explain such things in biological terms. Others see not so much hubris as hype: certain well-publicized findings, they fear, could turn out to be milestones on the road to an intellectual dead end.

It is undeniably true that neurobiological research is often pursued in a context of great ignorance. The brain remains an organ of mystery even in general, not to mention with regard to specific functions. “We don’t know” may be the most frequently used words in neurobiology, and they seem to be used with special frequency when the subject of sexual orientation comes up. Once, I mentioned to a researcher how often I heard these words on the lips of her colleagues, and she replied, “Good—then they’re saying the right thing.” In this context, and also considering that the subject matter is politically charged, professional rivalries are inevitable and occasionally bitter. Some of those involved in the research are motivated not only by scientific but also by personal concerns. Many of the scientists who have been studying homosexuality are gay, as am I.

Homosexuality’s invitation to biology has been standing for years. Homosexuals have long maintained that sexual orientation, far from being a personal choice or lifestyle (as it is often called), is something neither chosen nor changeable; heterosexuals who have made their peace with homosexuals have often done so by accepting that premise. The very term “sexual orientation,” which in the 1980s replaced “sexual preference,” asserts the deeply rooted nature of sexual desire and love. It implies biology.

Researchers can look back on two histories: a century-long, highly problematic psychological investigation of homosexuality, and a short but extremely complex history of biological research that started out as an examination of ovulation in rats. Three distinct but interrelated biological fields are involved in the recent work on sexual orientation: neuroanatomy, psychoendocrinology, and genetics.

 

The Background

 

Biologists embarked upon research into homosexuality in response to an intellectual vacuum created by the failure of other sciences to solve the riddle of sexual orientation. “Other sciences” mostly means psychiatry. As Michael Bailey and Richard Pillard, the authors of one of the most important genetic inquiries into homosexuality, have observed, decades of psychiatric research into possible environmental causes of homosexuality—that is to say, social and cultural causes—show “small effect size and are causally ambiguous.”
As a distinct concept, homosexuality is relatively recent. David Halperin points out in One Hundred Years of Homosexuality that the term itself first appeared in German (Homosexualität) in a pamphlet published in Leipzig in 1869; it entered the English language two decades later. That some human beings engage in sexual activity with others of the same sex has, of course, been noted since antiquity. Historically, however, the focus was on the acts themselves rather than on the actors. The historian John Boswell, of Yale, has noted that during the Middle Ages “same-sex sex” was regarded as a sin, but those who committed that sin were not defined as constituting a type of people different from others. Between the sixteenth and the eighteenth century same-sex sex became a crime as well as a sin, but again, those who committed such crimes were not categorized as a class of human being. This changed in the nineteenth century, when modern medicine and particularly the science of psychiatry came to view homosexuality as a form of mental illness. By the 1940s homosexuality was discussed as an aspect of psychopathic, paranoid, and schizoid personality disorders.

Having defined homosexuality as a pathology, psychiatrists and other doctors made bold to “treat” it. James Harrison, a psychologist who produced the 1992 documentary film Changing Our Minds, notes that the medical profession viewed homosexuality with such abhorrence that virtually any proposed treatment seemed defensible. Lesbians were forced to submit to hysterectomies and estrogen injections, although it became clear that neither of these had any effect on their sexual orientation. Gay men were subjected to similar abuses. Changing Our Minds incorporates a film clip from the late 1940s, now slightly muddy, of a young gay man undergoing a transorbital lobotomy. We see a small device like an ice pick inserted through the eye socket, above the eyeball and into the brain. The pick is moved back and forth, reducing the prefrontal lobe to a hemorrhaging pulp. Harrison’s documentary also includes a grainy black-and-white clip from a 1950s educational film produced by the U.S. Navy. A gay man lies in a hospital bed. Doctors strap him down and attach electrodes to his head. “We’re going to help you get better,” says a male voice in the background. When the power is turned on, the body of the gay man jerks violently, and he begins to scream. Doctors also tried castration and various kinds of aversion therapy. None of these could be shown to change the sexual orientation of the people involved.

Among those who looked into the matter was the sex researcher Alfred Kinsey, whose 1948 report Sexual Behavior in the Human Male showed homosexuality to be surprisingly common across lines of family, class, and educational and geographic background. In his book Being Homosexual, the psychoanalyst Richard Isay writes,

Kinsey and his co-workers for many years attempted to find patients who had been converted from homosexuality to heterosexuality during therapy, and were surprised that they could not find one whose sexual orientation had been changed. When they interviewed persons who claimed they had been homosexuals but were now functioning heterosexually, they found that all these men were simply suppressing homosexual behavior. . . and that they used homosexual fantasies to maintain potency when they attempted intercourse. One man claimed that, although he had once been actively homosexual, he had now “cut out all of that and don’t even think of men—except when I masturbate.”
Psychiatry not only consistently failed to show that homosexuality was a preference, a malleable thing, susceptible to reversal; it also consistently failed to show that homosexuality was a pathology. In 1956, in Chicago, a young psychologist named Evelyn Hooker presented a study to a meeting of the American Psychological Association. Hooker had during her training been routinely instructed in the theory of homosexuality as a pathology. A group of young gay men with whom she had become friendly seemed, however, to be quite healthy and well adjusted. One of them, a former student of hers, sat her down one day and, as she recalls in Changing Our Minds, said, “Now, Evelyn, it is your scientific duty to study men like me.” She demurred. It was only when a fellow scientist remarked to her, “He’s right—we know nothing about them,” that Hooker sought and received a study grant from the National Institute of Mental Health. She chose a group of thirty gay men as the objects of her research and thirty straight men as controls; none of the sixty had ever sought or undergone psychiatric treatment. “It was the first time [homosexuals] had been studied outside a medical setting or prison,” she says. “I was prepared, if I was so convinced, to say that these men were not as well adjusted as they seemed on the surface.”

Hooker administered psychological tests to her sixty subjects, including the Rorschach ink-blot test, producing sixty psychological profiles. She removed all identifying marks, including those indicating sexual orientation, and, to eliminate her own biases, gave them for interpretation to three eminent psychologists. One of these was Bruno Klopfer, who believed that he would be able to distinguish homosexuals from heterosexuals by means of the Rorschach test. As it turned out, none of the three could tell the homosexuals and heterosexuals apart. In side-by-side comparisons of matched profiles, the heterosexuals and homosexuals were indistinguishable, demonstrating an equal distribution of pathology and mental health. Reviewing Hooker’s results from a test in which the subject creates pictures with cutout figures, one of the interpreters, a psychologist named Edwin Shneidman, stumbled onto a particular subject’s orientation only when he came across a cutout scene depicting two men in a bedroom. Shneidman remembers, “I said to Evelyn, ‘Gee, I wish I could say that I see it all now, that this is the profile of a person with a homosexual orientation, but I can’t see it at all.'”

Hooker’s research throughout her long career was driven by the belief that for psychiatry to be minimally scientific, pathology must be defined in a way that is objective and empirically observable. Her study was the first of many showing that homosexuality could not be so defined as pathology. In 1973 the American Psychiatric Association removed homosexuality from its official Diagnostic and Statistical Manual, signifying the end of homosexuality’s official status as a disease. Today’s psychiatrists and psychologists, with very few exceptions, do not try to change sexual orientation, and those aspiring to work in the fields of psychiatry and psychology are now trained not to regard homosexuality as a disease.

 

 

Anatomy Lessons

 

With homosexuality moved from the realm of psychiatric pathology into the realm of normal variants on human sexual behavior, research efforts took a new turn. Psychiatry had succeeded in defining what homosexuality is not—not in explaining what it is. Questions of etiology, in this as in other psychiatric matters, thus became by default questions for neurobiology. Are homosexuals and heterosexuals biologically different? In thinking about this question, biologists have been greatly influenced by findings that involve what may be a related question: Just how, neurologically, do men differ from women?

In 1959, at the University of California at Los Angeles, the neuroendocrinologist Charles Barraclough found that if a female rat was injected shortly before or after birth with testosterone, a male sex hormone, the abnormal amount of this hormone would make the rat permanently sterile, unable to ovulate. “Ovulation” as used here is in part a technical term: it refers both to what a lay person would think of as ovulation—the movement of an egg from the ovary into the fallopian tube—and to the series of hormonal interactions that cause that event.

Rats have short estrous cycles. Every four days various glands in the rat’s body start pumping estrogens, or female sex hormones, into the bloodstream, setting in motion a series of chemical events. Estrogen levels reach a certain concentration and stimulate part of the hypothalamus, the small portion of the brain that regulates (among other things) body temperature, hunger, thirst, and sexual drive. The hypothalamus in turn stimulates the pituitary gland; the pituitary then releases a burst of something called luteinizing hormone, which causes the ovary to release an egg. Barraclnugh discovered that in female rats even a single perinatal exposure to testosterone will prevent this entire process from ever occurring. If that discovery was intriguing, a subsequent one was even more so: the discovery that male rats can ovulate—at least in the sense of going through the hormonal preliminaries. In 1965 Geoffrey Harris, a neuroendocrinologist at Oxford University, castrated a group of newborn male rats, depriving them of the testosterone from their testes. He found that if estrogen was injected into the bodies of these rats after they reached adulthood, it stimulated the hypothalamus, which initiated the sequence of hormone releases described above. The male rats obviously had no ovaries or wombs, but they went through the biochemical motions of ovulation. If one grafted an ovary onto a male rat, he would ovulate perfectly.

Further tests revealed a strange asymmetry. Whereas newborn male rats deprived of testosterone will, as Harris found, experience female-like ovulation, newborn female rats deprived of estrogen will continue to develop as females. In adulthood they will not seem somehow male. Although the rats’ ovaries have been removed, their brains will still produce the stimulus to ovulate. Scientists realized that without testosterone the genetic blueprint for masculinity was essentially worthless. Indeed, they learned, for a male rat’s brain to become truly organized as male, the rat must be exposed to testosterone within the first five days of life. After the fifth day the masculinizing window of opportunity is closed, and the genetic male will grow up with a “female” brain. In contrast, the brain of a female needs no estrogen for organization; left alone, it will become female.

Thus it came to be understood that what one might think of as the “default brain” for both sexes of the rat is feminine, and that testosterone is as necessary in the creation of a masculine brain as it is in the creation of masculine genitals. This concept, which is the basis of one approach to the neurobiological search for the origins of sexual orientation, is known as the “sexual differentiation of the brain.”

Roger Gorski, a neurobiologist at the University of California at Los Angeles who has long been involved in research on sexual differentiation, looked back recently on the development of his field: “We spent much of our professional careers trying to understand this process of sexual differentiation, and what functions happen within it—male sex behavior, female sex behavior, control of ovulation, control of food intake, body weight, aggressive behavior, some aspects of maternal behavior. You know why male dogs lift their legs when they pee? Because the brain has changed. So this is really a fundamental concept, that the brain is inherently female and to develop as male it must be exposed to masculinizing hormones.”

Several years after Harris’s experiment other researchers at Oxford University succeeded in confirming anatomically what the principle of the sexual differentiation of the brain had strongly implied: that an observable difference exists between the brains of male rats and those of female rats. In 1971 the anatomists Geoffrey Raisman and Pauline Field published a paper that compared the synapses, or connections between brain cells, in the hypothalamuses of male and female rats. The prevailing view at the time was that all structures of male and female brains were alike. Raisman and Field found that female and male rat brains differed in the number of synaptic connections between brain cells in the hypothalamus: females had more. Rat brains, which varied by sex in terms of function, also varied in terms of structural shape—were “sexually dimorphic.” In 1977 a team of neurobiologists led by Roger Gorski located a second sexual dimorphism, again in the rat hypothalamus: a small nucleus, or cluster of cells, five times larger in volume in the male rat than in the female. Gorski found that with the naked eye he could sex rats’ brains with almost 100 percent accuracy. Gorski’s team named the nucleus, logically, the sexually dimorphic nucleus. Its function is not known.

The groundwork had been laid in rodents. The next step was to see if sexual dimorphism of some kind could be found in the brains of human beings. In 1982 the cell biologist Christine de Lacoste-Utamsine and the physical anthropologist Ralph Holloway published in Science an examination of a structure in the human brain called the corpus callosum. The corpus callosum, which is made up of nerve fibers known as axons, is a long, narrow structure that connects and transmits information between the brain’s right and left hemispheres. It is one of the largest and most clearly identifiable portions of the brain, and has for years figured prominently in brain research. De Lacoste-Utamsing and Holloway found that the shape of a portion of the corpus callosum called the splenium differed so dramatically between the sexes, with the splenium being larger in women than in men, that impartial observers were able to sex brains easily by looking at this single feature. The De Lacoste-Utamsing and Holloway study is well known and frequently cited, despite the failure of many of the attempts to replicate it. Whether the dimorphism found by De Lacoste-Utamsing and Holloway truly exists remains a matter of considerable debate.

In 1985, three years after the publication of the De Lacoste-Utamsing and Holloway article, Dick Swaab, a researcher at the Netherlands Institute for Brain Research, in Amsterdam, reported that he, too, had found evidence of sexual dimorphism in human brains—in the form of a human homologue of the sexually dimorphic nucleus that Gorski had found in rats.

Swaab announced an even more remarkable discovery five years later, in 1990. He had found, he wrote in an article in the journal Brain Research, that a cluster of cells in the human brain called the suprachiasmatic nucleus was dimorphic—but dimorphic according to sexual orientation rather than sex. Swaab said that the suprachiasmatic nucleus was nearly twice as large in homosexual men as it was in heterosexual men.

If true, this was something wholly new: an anatomical difference between homosexuals and heterosexuals.

Simon Levay is a young neurobiologist who at the time of Swaab’s second discovery was conducting research at the Salk Institute, in La Jolla, California. LeVay would soon become the author of what is surely the most publicized neurobiological article on homosexuality that has appeared to date. I spoke with him one day recently in his West Hollywood apartment. LeVay is a wiry, muscular man, remarkably intense. Perhaps the most striking thing about him is the way he talks. In a crisp British accent he zeroes in on each point and then moves on with an air of impatience.

“You shouldn’t draw such a distinction between biological and psychological mechanisms,” he chided me at one point during our conversation. “What people are really getting at is the difference between innately determined mechanisms and culturally determined mechanisms, but people screw that up and say that’s the difference between biology and psychology. It isn’t. It’s two different approaches for looking at the same thing: the mind. Biologists look at it from the bottom up, from the level of synapses and molecules, and psychologists are looking at it from the top down, at behavior and such.”

LeVay had been intrigued by Swaab’s research, but he was troubled by the fact that the portion of the brain examined by Swaab seemed to have nothing to do with the regulation of sexual behavior, at least not in animals. The suprachiasmatic nucleus governs the body’s daily rhythms; dimorphism there according to sexual orientation might be provocative, certainly, but it would seem to constitute an effect, not a cause. Why not check out the hypothalamus, a region that is intimately involved with sexual behavior?

Laura Allen, a postdoctoral assistant in Gorski’s laboratory, had identified four small groups of neurons in the anterior portion of the hypothalamus, naming them the interstitial nuclei of the anterior hypothalamus (INAH) 1, 2, 3, and 4. Allen’s research had shown that INAH 2 and INAH 3 were sexually dimorphic in human beings—significantly larger in men than in women. Was it possible that these nuclei were dimorphic according to sexual orientation as well? That was the focus of LeVay’s research, and he presented his conclusions in a short paper titled “A Difference in Hypothalamic Structure Between Heterosexual and Homosexual Men.” It was published in Science in August of 1991. In the introduction LeVay defined sexual orientation as “the direction of sexual feelings or behavior toward members of one’s own or the opposite sex” and hypothesized that Allen’s INAH nuclei were involved in the generation of “male-typical sexual behavior.” He went on,

I tested the idea that one or both of these nuclei exhibit a size dimorphism, not with sex, but with sexual orientation. Specifically, I hypothesized that INAH 2 or INAH 3 is large in individuals sexually oriented toward women (heterosexual men and homosexual women) and small in individuals sexually oriented toward men (heterosexual women and homosexual men).

 

LeVay dissected brain tissue obtained from routine autopsies of forty-one people who had died at hospitals in New York and California. There were nineteen homosexual men, all of whom had died of AIDS; sixteen presumed heterosexual men, six of whom had been intravenous drug abusers and had died of AIDS; and six presumed heterosexual women. No brain tissue from lesbians was available. LeVay’s conclusions included the following:

INAH 3 did exhibit dimorphism…. [T]he volume of this nucleus was more than twice as large in the heterosexual men … as in the homosexual men…. There was a similar difference between the heterosexual men and the women…. These data support the hypothesis that INAH 3 is dimorphic not with sex but with sexual orientation, at least in men.

 

The results were sufficiently clear to LeVay to allow him to state, “The discovery that a nucleus differs in size between heterosexual and homosexual men illustrates that sexual orientation in humans is amenable to study at the biological level.”

The study, as LeVay himself readily admits, has several problems: a small sample group, great variation in individual nucleus size, and possibly skewed results because all the gay men had AIDS (although LeVay found “no significant difference in the volume of INAH 3 between the heterosexual men who died of AIDS and those who died of other causes”). As of this writing, LeVay’s findings have yet to be replicated by other researchers. LeVay himself has extended his search for dimorphism according to sexual orientation to the corpus callosum, which he is studying by means of magnetic-resonance imaging. Until his original findings are confirmed, the notion that homosexuals and heterosexuals are in some way anatomically distinct must hold the status of tantalizing supposition.

It needs also to be remembered that, as noted earlier, the issue of dimorphism of any kind in the brain is hotly contested. The idea that the brains of heterosexuals and homosexuals may be different morphologically is derived from the idea that the brains of men and women are different morphologically—recall the corpus callosum study by De Lacoste-Utamsing and Holloway. But that study is itself problematic, efforts to replicate it having turned up inconsistent results. Anne Fausto-Sterling is a developmental geneticist at Brown University. She, along with William Byne, a neurobiologist and psychiatrist at Columbia University, has been among the chief critics of neurobiological investigations of homosexuality. Fausto-Sterling during an interview not long ago itemized some of the results from a long line of attempts to replicate sexual dimorphism: “1985: no sex differences in shape, width, or area. 1988: three independent observers unable to distinguish male from female. 1989: women had smaller callosal areas but larger percent of area in splenium, more-slender CCs, and more-bulbous splenium.” A new corpus callosum study by Laura Allen, conducted in 1991, did find sexual dimorphism—and the debate continues. Part of the difficulty is methodological, involving whose brains are being compared, and how. Dead people or living people? Old or young or mixed? Healthy or sick? By means of brain sections or magnetic-resonance imaging? LeVay calls studies of the corpus callosum “the longest-running soap opera in neurobiology.” And, of course, he himself is now part of the cast.

Even if LeVay’s hypothalamus study stands up to scrutiny, it will not justify drawing extravagant conclusions. Establishing a distinction is not the same thing as finding a cause. Anatomy is not etiology, but it may offer a starting point for a journey backward in search of the ultimate origins of sexual orientation. That journey takes us into the realm of hormones and genetics.

 

 

The Puzzles of Chemistry

 

In a large room at the UCAL department of anatomy, Roger Gorski and I recently stood facing a dozen black-topped lab tables, each below a ceiling-mounted video monitor. We were about to watch a tape of rats having sex.

Gorski, an eternally cheerful, almost elfin man of fifty-seven, was energetically describing the tape. “There are six couples,” he explained, though at the moment I saw only one uninterested-looking white rat. “That’s an unaltered female,” he said. “They’re going to put in another female that has been injected with testosterone.” Sure enough, someone’s hand reached down into the screen and a second rat landed in the cage. The rats at first edged around each other, but in just a few seconds on the dozen monitors I saw the testosterone-injected female begin to sniff the other female rat and then mount her aggressively. At the lab tables a handful of medical students went on with their work, paying no attention. After a few moments the tape cut to two males, one perinatally castrated and injected with estrogen, one unaltered. After some initial maneuvering the castrated male responded to the advances of the unaltered male by bending his back and offering himself in what was to me indistinguishable from female-rat lordosis—behavior indicating receptivity to sex, pictures of which Gorski had shown me in his office. The altered rat submitted as the other male mounted him. The tape continued with similar scenes. It was quite dramatic.

Such research in animals has led to hypotheses that hormones are, in some way, a cause of homosexuality in human beings. No one, of course, suggests that the sexuality of rats and that of human beings are strictly comparable; some critics of neurobiological research on homosexuality question the utility of animal models entirely. Nonetheless, it was investigations involving animals that got researchers thinking.

Of the scientists who have concentrated on hormonal or psychoendocrinological studies of homosexuality, Günter Dörner, of Germany, is one of the best known. In the 1970s Dorner classified homosexuality as a “central nervous pseudohermaphroditism,” meaning that he considered male homosexuals to have brains with the mating centers of women but, of course, the bodies of men. For decades endocrinologists had speculated that because male sex hormones are known to be responsible in human beings for masculine body characteristics and in animals for certain aspects of male sexual behavior, it follows that adult homosexual men should have lower levels of testosterone, or else higher levels of estrogen, in the bloodstream than adult heterosexual men, and that homosexual and heterosexual women should display the opposite pattern. This is known as the “adult hormonal theory” of sexual orientation, and Dorner claimed that some initial studies bore it out.

In 1984 Heino Meyer-Bahlburg, a neurobiologist at Columbia University, analyzed the results of twenty-seven studies undertaken to test the theory. According to Meyer-Bahlburg, a score of the studies in fact showed no difference between the testosterone or estrogen levels of homosexual and heterosexual men. Three studies did show that homosexuals had significantly lower levels of testosterone, but Meyer-Bahlburg believed that two of them were methodologically unsound and that the third was tainted by psychotropic drug use on the part of its subjects. Two studies actually reported higher levels of testosterone in homosexual men than in heterosexual men, and one unhelpfully showed the levels to be higher in bisexuals than in either heterosexuals or homosexuals.

As it came to be widely accepted that adult hormone levels were not a factor in sexual orientation, scientists shifted their attention to prenatal hormone exposure. Many of the glands in a human being’s hormone system are busily functioning even before birth—tiny hormone factories that produce the chemicals that help to mold the person who will eventually emerge. Perhaps, it was thought, different levels of prenatal hormones produce different sexual orientations. For obvious reasons, the sometimes brutal hormonal experiments done on monkeys and rats cannot be done on human beings, but nature at times provides a narrow window onto the mysteries of prenatal hormonal effects in ourselves.

Congenital adrenal hyperplasia (CAM) has been called by Meyer-Bahlburg a “model endocrine syndrome” for examining the effects of abnormal amounts of prenatal sex hormones. CAH, which can affect both males and females, is caused by a simple problem: an enzyme defect makes it impossible for a fetus’s adrenal gland to produce cortisol, an important hormone. In a normal fetus, as the adrenal gland produces cortisol, the brain stands by patiently, waiting for the signals that the cortisol level is appropriately high and production can be shut off. But in CAH fetuses, which lack the enzyme to create cortisol, the brain doesn’t get those signals, and so it orders the adrenal gland to continue production. The adrenal gland continues pumping out what it thinks is cortisol, but it is unknowingly producing masculinizing androgens. It dumps these into the fetus’s system, thereby overexposing it to male hormones.

The consequences are most dramatic in females. Once, in his office, Roger Gorski dug into a desk drawer and grabbed a few photographs. “What sex is it?” he asked. I squinted at close-ups of a child’s genitals and saw a penis, plain as day. “It’s a boy,’, I said confidently. Gorski’s eyebrows shot up. “Where are the testicles?” he asked. I looked closer. Oops.

This was a CAH baby. In this case, Gorski told me, the doctors had decided at the time of birth that the child was a boy with undescended testicles, a relatively common and minor condition. But in fact I was looking at a genetic female.

With surgery a CAH female’s external genitals can be made to look feminine, as her internal apparatus already fully is, and she will be raised as a girl. But hormones may have already had their effect in an area that plastic surgery cannot touch: the brain. Or at least so proponents of the prenatal-hormone theory of sexual orientation would argue. The sexual orientation of CAH females tends to bear them out. A 1984 study by the Johns Hopkins University sex researcher John Money found that 37 percent of CAH women identified themselves as lesbian or bisexual; the current estimate of the proportion of lesbians in the general female population is from two to four percent.

One possible clue as to whether the prenatal-hormone theory of sexual orientation is a profitable line of inquiry involves something called luteinizing-hormone (LH) feedback. The brain releases several hormones, including LH, which initiate the development of an egg in a woman’s ovary. As the egg develops, the ovary releases increasing amounts of estrogen, stimulating the brain to produce more LH, which in turn promotes the production of still more estrogen. The process is called positive feedback. In men, estrogen usually acts to suppress the production of luteinizing hormone—it results in negative feedback. These differences in LH feedback in human beings, together with the discovery that male rats hormonally altered after birth will display both positive LH feedback and same-sex sexual behavior, led some researchers to a hypothesis. They speculated that gay men, their brains presumably not organized prenatally by testicular hormones, just as women’s are not, would show a positive LH feedback, like that of a heterosexual female, rather than the negative feedback of the typical heterosexual male. If such feedback were to be found consistently in homosexual men—by means of chemical analysis of the blood after injection with estrogen—could this not be taken as evidence that some decisive prenatal hormonal event, with important bearing on subsequent sexual orientation, had indeed occurred?

This line of inquiry has given rise to an active field of study that as yet has little to show for itself. The uncertainties are of two kinds. The first one involves the following question: Do LH feedback patterns of the sort being sought in fact exist in human beings? The second comes down to this: Even if LH feedback patterns of the sort being sought do exist, will they really tell us anything about events that occurred before birth? Unfortunately, neuroscientists lack unequivocal answers to both questions, despite considerable efforts. Different studies have yielded conflicting data. No one has yet come up with what one neurobiologist facetiously terms a “gay blood test.”

In an article published in 1990 in the Journal of Child and Adolescent Psychopharmacology, Heino Meyer-Bahlberg surveyed the work done so far on hormonal research in general and concluded: “The evidence available to date is inconsistent, most studies are methodologically unsatisfactory, and alternative interpretations of the results cannot be ruled out.” On the other hand, Meyer-Bahlberg went on, “not all potential avenues to a psychoendocrine explanation of homosexuality have been exhausted.”

Among the unexhausted avenues is one being explored by Richard Pillard.

A PSYCHIATRIST AT THE BOSTON UNIVERSITY SCHOOL of Medicine, Richard Pillard is a tall, pleasant man in his fifties with a neatly trimmed moustache and a relaxed manner. Even when talking seriously, he remains goodnatured. When we spoke one afternoon in his Boston townhouse, he joked that he is uniquely equipped to investigate whether homosexuality has a biological basis: he, his brother, and his sister are gay, and Pillard believes that his father may have been gay. One of Pillard’s three daughters from a marriage early in life is bisexual. This family history seems to invite a biological explanation, and it made Pillard start thinking about the origins of sexual orientation.

Pillard says that it had long puzzled him why transsexuals—men or women who wish to live in bodies of the opposite sex—are so different from gay people: “You’d think they’d be on the far end of the spectrum, the ‘gayest of the gay.'” And yet transsexuals are not in fact gay. Whereas gay men, quite comfortably and unalterably, see themselves as men, male transsexuals see themselves as women trapped in men’s bodies. Pillard and a colleague, James Weinrich, a psychobiologist at the University of California at San Diego, began to theorize that gay men are men who in the womb went through only a partial form of sexual and psychosexual differentiation. More precisely, Pillard and Weinrich theorized that although gay men do undergo masculinization—they are, after all, fully male physically—they go incompletely if at all through another part of the process: defeminization.

As fetuses, Pillard points out, human beings of both sexes start out with complete female and male “anlages,” or precursors of the basic interior sexual equipment—vagina, uterus, and fallopian tubes for women, and vas deferens, seminal vesicles, and ejaculatory ducts for men. These packages are called the Mullerian (female) and Wolffian (male) ducts, and are tubes of tissue located in the lower abdomen. How do the sexual organs develop? It happens differently in men and women.

At the moment of conception an embryo is given its chromosomal sex, which determines whether it will develop testes or ovaries. In female human beings (as in female rats) the female structures will simply develop, without any help from hormones; the Wolffian duct will shrivel up. The process of becoming male, however, is more complex. Where women need none, men need two kinds of hormones: androgens from the testes to prompt the Wolffian duct into development, and a second substance, called Mullerian inhibiting hormone, to suppress the Mullerian duct and defeminize the male fetus.

Pillard speculates that Mullerian inhibiting hormone, or a substance analogous to it, may have brain-organizing effects. Its absence or failure to kick in sufficiently may prevent the brain from defeminizing, thereby creating what Pillard calls “psychosexual androgyny.” In this view, gay men are basically masculine males with female aspects, including perhaps certain cognitive abilities and emotional sensibilities. Lesbian women could be understood as women who have some biologically induced masculine aspects.

An experimental basis is provided by research by the psychiatrist Richard Green, of the University of California at Los Angeles, which shows that children who manifest aspects of gender-atypical play are often gay. Green has concluded that an inclination toward gender-atypical play in prepubescent boys—for example, dressing in women’s clothes, playing with dolls, or taking the role of the mother when playing house—indicates a homosexual orientation 75 percent of the time. If that is true, it is important, because it would be an example of a trait linked to sexual orientation which does not involve sexual behavior—suggesting how deeply rooted sexual orientation is. Discussing this line of research, Simon LeVay told me, “It’s well known from animal work that sex-typical play behavior is under hormonal control. Robert Goy [at the University of Wisconsin at Madison] has done many studies over the years showing that you can reverse the sex-typical play behavior of infant monkeys by hormonal manipulations in prenatal life. [Play] is an example of a sex-reversed trait in gay people that’s not directly related to sex. It’s not sex, it’s play. When you get to adulthood, these things become blurred. It’s easier to tell a gay kid than a gay adult–kids are much of a muchness. Most gay men, even those who are very macho as adults, recall at least some gender-atypical behavior as children.”

The Pillard-Weinrich theory also accords with what Green refers to as male “vulnerability” during the process of sexual differentiation. A considerably larger number of male embryos come into existence than female embryos, and yet males and females come into the world in about the same numbers. Therefore, phenomena linked to sex must reduce the number of males who survive to term. Many disorders are, in fact, more common in men than women, and some of these could result from problems originating in masculine differentiation. Although good statistics do not exist, it appears that there may be two gay men for every gay woman, which would be consistent with the vulnerability theory.

It is important to remember that although homosexuals and heterosexuals may be “sex-reversed” in some ways, in other ways they are not. For example, neither gay nor straight men tend to be confused on the subject of what sex they are: male. LeVay says, “It’s not just that you look down and see you have a penis and you say, ‘Oh, I’m a boy. Great.’ I think there must be some internal representation of what sex you are, independent of these external signals like the appearance of your body. I think most gay men are aware of some degree of femininity in themselves, yet there is no reversal of gender identity.” Gay men and straight men also seem to display an identical strong drive for multiple sexual partners; lesbians and straight women seem to be alike in favoring fewer sexual partners.

The evidence from hormonal research may circumstantially implicate biology in sexual orientation, but it is far from conclusive. William Byne raises a warning flag: “If the prenatal-hormone hypothesis were correct, then one might expect to see in a large proportion of homosexuals evidence of prenatal endocrine disturbance, such as genital or gonadal abnormalities. But we simply don’t find this.” Moreover, the hormonal research does not answer the question of ultimate cause. If hormones help to influence sexual orientation, what is influencing the hormones?

 

 

The Genetic Quest

 

In 1963 Kulbir Gill, a visiting scientist from India working at Yale University, was conducting research into genetic causes of female sterility. His experiments involved exposing the fruit fly Drosophila melanogaster, that workhorse of genetic research, to X-rays, and observing the behavior of the resulting offspring. Gill noticed that a certain group of mutant male flies were courting other males, following each other and vibrating their wings to make characteristic courtship “songs.” Gill published his findings in a short note in the publication Drosophila Information Service and then returned to the question of female sterility.
A decade later Jeffrey Hall, a biologist at Brandeis University, followed up on Gill’s odd discovery. Every discovered Drosophila gene mutation is given a name, and Gill had called his mutation “fruity.” Hall, considering this name to be denigrating, redubbed it, still somewhat tongue-in-cheek, “fruitless.” Hall explains that the fruitless mutation produces two distinct behaviors. First, fruitless-bearing male flies, unlike nonmutant male flies, actively court other males as well as females, although for reasons that remain poorly understood, they are unable actually to achieve intercourse with members of either sex. Second, fruitless-bearing males elicit and are receptive to courtship from other males, which nonmutant males reject.

Fruit flies can live for two or three months, and this “bisexual” fly strain has existed behaviorally unchanged through hundreds of generations. Some gene mutations are lethal to flies; fruitless is not one of these, nor does it cause illness. It is, Hall says, a nonpathological genetic mutation that causes a consistent, complex behavior. And fruitless displays an anatomical sexual dimorphism, bringing LeVay’s study to mind. In the abdomen of male Drosophila flies there is a muscle, the so-called muscle of Lawrence, whose function is unknown; female fruit flies don’t have it, and neither do fruitless males.

Although fruitless flies don’t mate, the perpetuation of the fruitless trait is made possible by the fact that it is recessive–a full pair of the mutations is needed for fruitless behavior to be expressed. When males that carry a single fruitless gene mate with a fruitless-carrying female, a percentage of their offspring will carry the full pair and display typical fruitless behavior. If a genetic component of homosexuality in human beings exists, it could possibly operate by means of a comparable mechanism.

Angela Pattatucci, a geneticist at the National Institutes of Health, gave me a demonstration a few months ago in her lab. She took a small glass container of tiny Drosophila flies, popped off the top, and plugged an ether-soaked cotton ball into the mouth. Within a few seconds the flies were lying stunned on the glass floor. Using a plastic stick Pattatucci separated out a few of the flies into a larger glass jar. I looked at a group of males and females through a microscope, their bodies vibrating, red eyes bulging. Pattatucci showed me how to differentiate the genitalia at the end of the abdomen–smooth and light-colored for females, furry and dark for males.

Pattatucci said that researchers are relatively close to finding the actual fruitless gene. It is already known that fruitless is located physically on the right arm of the third chromosome. After establishing the precise location (or locations) of the mutation, researchers can determine the sequence of biochemical information in fruitless’s genetic code—the order of thousands of units of the basic genetic components adenine, thymine, guanine, and cytosine. Once the combination is known, the search can begin for a similar combination—a fruitless analogue—in human beings.

In the jar the males, separated out, eventually came back to awareness. “Watch that one,” Pattatucci said, pointing to a fly that had come up behind another fly, vibrating his wings in courtship. He then climbed on top of the male he was courting. I watched the two flies, one atop the other, the one on the bottom wandering around as if a bit bored. As noted, for a fruitless fly that is as far as things can go.

I once asked Jeffrey Hall if courtship alone could be satisfying for a fly. “Could be,” he said. “Maybe it’s delicious, maybe he’s frustrated. But this becomes ludicrous. How do you know when a fruit fly is frustrated?” It is an important point: the danger of anthropomorphizing insect behavior is great, and I found myself doing it almost by reflex when watching Pattatucci’s flies. How can we equate fly behavior with a vast something that in human beings generates aesthetic and intellectual perceptions—with something that encompasses emotional need and love and the pain of love? So Hall is careful to describe fruitless as “a mutation that leads to a mimic of bisexuality.” He is skeptical that finding a fruitless analogue will lead to a full explanation of human homosexuality. DNA analogues for all sorts of fruit-fly genes do exist in human beings, and the process of looking for them is relatively straightforward. But, as Hall points out, “it is very unlikely that the genetics of homosexuality will ever devolve to a single factor in humans with such major effects as it has in Drosophila.”

When biologists are interested in establishing whether genetics is involved in the appearance of certain characteristics or conditions, one obvious place to look is among people who are closely related to one another. In “A Genetic Study of Male Sexual Orientation,” a study that has now achieved almost as much renown as LeVay’s, the Northwestern University psychologist Michael Bailey and Boston University’s Richard Pillard compared fifty-six “monozygotic” twins (identical twins, from the same zygote, or fertilized egg), fifty-four “dizygotic” (fraternal) twins, and fifty-seven genetically unrelated adopted brothers. Identical twins are important in sexual-orientation research because, of course, they have identical genomes, including the sex-chromosome pair. If homosexuality is largely genetic in origin, then the more closely related that people are, the greater should be the concordance of their sexual orientation.

That is, in fact, what the study found. Bailey and Pillard reported a gay-gay concordance rate of 11 percent for the adoptive brothers, 22 percent for the dizygotic twins, and 52 percent for the monozygotic twins. The findings suggest that homosexuality is highly attributable to genetics—by some measures up to 70 percent attributable, according to Pillard. This figure is based on something geneticists call “heritability,” a painstakingly calculated indicator of how much genes have to do with a given variation among people. If heritability is less than 100 percent, then the characteristic being studied is by definition “multifactorial.” Eye color is 100 percent dependent on genetics. Height, on the other hand, though about 90 percent genetic, is also affected by nutrition, and thus is multifactorial.

If a large contribution to homosexuality comes from genes; where does the rest of it come from? The range of environmental and biological inputs a developing child receives is both enormous and enormously complex. “Whatever the other variables are,” Pillard says, “they must be present early in life. I think this because the genderatypical behavior that so strongly prefigures an adult homosexual orientation can be observed early in development.” And he goes on: “There certainly could be different paths to the same outcome. With individual cases, there are doubtless some that are mostly or all genes, and others that might be all environment. Our analysis [of twins] doesn’t say anything about the individual.” Jeffrey Hall can be so underwhelmed by the prospect of finding a human analogue of the fruitless mutation because, as he points out, if we do find it, we still will not have fully accounted for the etiology of homosexuality even in identical twins. “You will effectively know nothing from this genetic knowledge,” Hall says. A behavior as simple as jumping, he notes, is quite complex genetically, having to do with all kinds of genes and other, unknown factors. He says, “We are not about to create a genetic surgical procedure which makes you Michael Jordan.” LeVay made the same point in the course of our conversation: “It’s one thing to say that genes are involved, as they almost certainly are. It’s a whole other thing to actually identify those genes, because homosexuality may be polygenic, with each gene having a small effect. ”

Whatever the uncertainties ahead, though, the important point is that the genetic work is already fairly compelling. A new Bailey and Pillard genetic study of lesbian twins, to be published soon in the Archives of General Psychiatry, echoes the researchers’ original male-twin findings with strikingly similar results. “We’re getting a lot of consistency where we should be getting it,” Bailey says.

The most interesting question is perhaps becoming not whether genetics plays a role in homosexuality but how. Why does nature preserve genes that influence sexual behavior and yet do not facilitate reproduction? Does less than 100 percent heritability mean that the Bailey and Pillard study is incompatible with a bipolar model of sexual orientation? In his study LeVay defined homosexuality in terms of the sex of a person’s sexual-object choice: either men or women, either homosexual or heterosexual. Pillard and Bailey’s multifactorial model suggests a shaded continuum of sexual orientations, and of origins and causes, more complex and subtle than a simple either-or model can accommodate, and closer to what may be the quirks and ambiguities of our real lives.

 

The Ramifications of Science

 

What does it all mean? As we have seen, scientists must sift for their conclusions through ambiguous results from a disparate group of studies that are excruciatingly difficult to interpret. Yet even at this relatively early date, out of the web of complexities it is becoming ever clearer that biological factors play a role in determining human sexual orientation. Richard Green said to me, “I suspect that at least in your lifetime we will find a gene that contributes substantially to sexual orientation.” Michael Bailey says, “I would—and have—bet my career on homosexuality’s being biologically determined.” The pace of neurobiological and genetic research is only increasing.
The search is not without its opponents. Some, recalling earlier psychiatric “treatments” for homosexuality, discern in the biological quest the seeds of genocide. They conjure up the specter of the surgical or chemical “rewiring” of gay people, or of abortions of fetal homosexuals who have been hunted down in the womb. “I think all of us working in this field,” Pattatucci says, “have delusions of grandeur in thinking we can control the way this knowledge will be used.” Certainly the potential for abuse is there, but that is true of much biomedical knowledge. It is no reason to forswear knowledge of ourselves, particularly when the potential benefits are great.

Some of the benefits could be indirect. Laura Allen points out, for example, that there are many now-mysterious diseases—autism, dyslexia, schizophrenia—that affect men and women differently, hiding inside parts of the human mind and body that we cannot penetrate. Neurobiological research into sexual differentiation may help us to understand and cure these diseases, as well as to unlock other mysteries—the mysteries of sexuality.

And then there is the question with which we began—that of the acceptance of gay people in American society. The challenge posed by homosexuality is one of inclusion, and, as Evelyn Hooker would say, the facts must be allowed to speak. Five decades of psychiatric evidence demonstrates that homosexuality is immutable, and nonpathological, and a growing body of more recent evidence implicates biology in the development of sexual orientation.

Some would ask: How can one justify discriminating against people on the basis of such a characteristic? And many would answer: One cannot. Yet it would be wise to acknowledge that science can be a rickety platform on which to erect an edifice of rights. Science can enlighten, can instruct, can expose the mythologies we sometimes live by. It can make objective distinctions—as, for example, between sexual pathology on the one hand and sexual orientation on the other. But we cannot rely on science to supply full answers to fundamental questions involving human rights, human freedom, and human tolerance. The issue of gay people in American life did not arise in the laboratory. The principles needed to resolve it will not arise there either.

ref:http://www.theatlantic.com/magazine/archive/1997/06/homosexuality-and-biology/4683/?single_page=true

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My Gens made me do it … Book

January 11, 2012 at 6:46 pm (Sicence)

Contents

Introduction

Ch1

Ch2

Ch3

Ch4

Ch5

Ch6

Ch7

Ch8

Ch9

Ch10

Ch11

Ch12

summary

index

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Scientific Evidence

January 11, 2012 at 6:38 pm (Sicence)

Nine Common Misconceptions about Homosexuality

Links to an external PDF file.

Article by David Myers, professor of Psychology at Hope College http://davidmyers.org/sexorient/textbksumm7e.html

Much of the false data used to support the untruth that homosexuality is a “sickness” is a product of Paul Cameron, a psychologist discredited by the APA. Link below for a complete expose on Mr. Cameron and his false data:
http://psychology.ucdavis.edu/rainbow/html/facts_cameron.html

Sexual Orientation and Science

The following article is a very helpful summary of the current state of scientific research on sexual orientation. I met its author, Dr. David G. Myers, during a Soulforce presentation at Hope College in Holland, Michigan, where he is a distinguished Professor of Psychology.

Link to whole essay: http://www.hope.edu/lib/special/dmyers.html

Dr. Myers’ textbooks in psychology are widely used in schools across North America. This excerpt is from David G. Myers’Exploring Psychology 4th edition (Worth Publishers, 1999). Excerpted and reformatted with the permission of Worth Publishers. A similar section appears in Dr. Myers’Psychology 5th edition (Worth Publishers, 1998).

SEXUAL ORIENTATION

We express the direction of our sexual interest in our sexual orientation–our enduring sexual attraction toward members of a particular gender.

As far as we know, all cultures in all times have been predominantly heterosexual (Bullough, 1990). Yet, cultures vary in their attitude toward homosexuality. Whether a culture condemns and punishes homosexuality or views it as an acceptable alternative, homosexuality survives and heterosexuality prevails.

Homosexual people often recall childhood play preferences like those of the other sex (Bailey & Zucker, 1995). But most homosexual people report not becoming aware of same-gender sexual feelings until during or shortly after puberty, and not thinking of themselves as gay or lesbian until around age 20 (Garnets & Kimmel, 1990).

How many people are exclusively homosexual?

Until recently, the popular press assumed a homosexuality rate of 10 percent. But in both Europe and the United States, more than a dozen national surveys in the early 1990s explored sexual orientation, using methods that protected the respondent’s anonymity. Their results agree in suggesting that a more accurate figure is about 3 or 4 percent of men and 1 to 2 percent of women (Laumann & others, 1994; Smith, 1996).

Less than 1 percent of the respondents reported being actively bisexual, but a larger number of adults reported having had an isolated homosexual experience. And most people said they had had an occasional homosexual fantasy.

Although health experts find it helpful to know sexual statistics, numbers do not decide issues of human rights. Similarly, it’s helpful in manufacturing school desks to know that about 10 percent of people are left-handed. But whether left-handers are 3 percent or 10 percent of the population doesn’t answer the moral question of whether lefties should enjoy equal rights.

What does it feel like to be homosexual in a heterosexual culture?

One way for heterosexual people to understand is to imagine how they would feel…

• if they were to be ostracized or fired for openly admitting or displaying their feelings toward someone of the other sex;
• if they were to overhear people making crude jokes about heterosexual people;
• if most movies, TV shows, and advertisements portrayed (or implied) homosexuality; and
• if their family members were pleading with them to change their heterosexual life-style and to enter into a homosexual marriage.

Facing such reactions, homosexual people often struggle with their sexual orientation.

At first, they may try to ignore or deny their desires, hoping they will go away. But they don’t.

Then they may try to change, through psychotherapy, willpower, or prayer. But the feelings typically persist, as do those of heterosexual people–who are similarly incapable of becoming homosexual (Haldeman, 1994).

Eventually, homosexuals may accept their orientation — by electing celibacy (as do some heterosexuals);

• by engaging in promiscuous sex (a choice more commonly made by men than by women);
• or by entering into a committed, long-term love relationship (a choice more often made by women than by men) (Peplau, 1982; Weinberg & Williams, 1974).

Most psychologists today view sexual orientation as neither willfully chosen nor willfully changed.

Sexual orientation in some ways is like handedness: Most people are one way, some the other. A very few are truly ambidextrous. Regardless, the way one is endures.

Nor is sexual orientation linked with psychological disorder or sexual crime. “Child molester” is not a sexual orientation. Some homosexuals do abuse children, but most child molesters are heterosexual males (Gonsiorek, 1982).

These facts led the American Psychiatric Association in 1973 to drop homosexuality from its list of “mental illnesses.” Understanding Sexual Orientation

If our sexual orientation is indeed something we do not choose and cannot change, then where do these preferences come from? How do we move toward either a heterosexual or a homosexual orientation? Is homosexuality linked with problems in a child’s relationships with parents, such as with a domineering mother and an ineffectual father or a possessive mother and a hostile father? As children, were many homosexuals molested, seduced, or otherwise sexually victimized by an adult homosexual? Are children who observe homosexual role models (such as parents) more likely to become homosexual?

Consider the findings of lengthy Kinsey Institute interviews with nearly 1000 homosexuals and 500 heterosexuals (Bell & others, 1981; Hammersmith, 1982). The investigators assessed nearly every imaginable psychological cause of homosexuality–parental relationships, childhood sexual experiences, peer relationships, dating experiences.

Their findings: Homosexuals were no more likely than heterosexuals to have been smothered by maternal love, neglected by their father, or sexually abused.

More recent studies have also found that sons of homosexual men were not more likely to become gay if they lived with their gay dad, and that 9 in 10 children of lesbian mothers developed into heterosexuals (Bailey & others, 1995; Golombok & Tasker, 1996).

If even being reared by a homosexual parent has no appreciable influence on sexual orientation, then having a gay or lesbian teacher or bus driver also seems unlikely to have an appreciable influence.

Homosexual people do, however, appear more often in certain populations:

In America’s dozen largest cities, the percentage of men identifying themselves as gay jumps to 9 percent, compared with only 1 percent in rural areas (Binson & others, 1995; Laumann & others, 1994).

One study of the biographies of 1004 eminent people found homosexual and bisexual people overrepresented (11 percent of the sample), especially among poets (24 percent), fiction writers (21 percent), and artists and musicians (15 percent) (Ludwig, 1995).

For uncertain reasons, men who have older brothers are somewhat more likely to be gay, report Ray Blanchard and his colleagues (1995, 1996a,b, 1997). Assuming the odds of homosexuality are roughly 3 percent among first sons, they rise to 4 percent among second sons and 5 percent for third sons.

So, what determines sexual orientation?

One theory proposes that people develop same-sex erotic attachments if segregated by gender at the time their sex drive matures (Storms, 1981). But even in a tribal culture in which homosexual behavior is expected of all boys before marriage, heterosexuality prevails (Money, 1987). (As this illustrates, homosexual behavior does not always indicate a homosexual orientation.)

Another theory proposes the opposite: that people develop romantic attachments to those who differ from, and thus are more fascinating than, the peers they associated with while growing up (Bell, 1982).

The bottom line from a half-century’s theory and research: If there are environmental factors that influence sexual orientation, we do not yet know what they are. If someone were to ask me, “What can I do to influence my child’s sexual orientation?” my answer would have to be “I haven’t a clue.”

The Brain and Sexual Orientation

New research indicates that sexual orientation is at least partly physiological. Researcher Simon LeVay (1991) discovered this while studying sections of the hypothalamus taken from deceased heterosexual and homosexual people.

As a gay scientist, LeVay wanted to do “something connected with my gay identity,” but he knew he had to avoid biasing the results. So he did the study “blind,” without knowing which donors were gay. After nine months of peering through his microscope at a cell cluster he thought might be important, LeVay sat down one morning and broke the codes.

His discovery: The cell cluster was reliably larger in heterosexual men than in women and homosexual men. As the brain difference became apparent, “I was almost in a state of shock … I took a walk by myself on the cliffs over the ocean. I sat for half an hour just thinking what this might mean” (LeVay, 1994).

It should not surprise us that brains differ with sexual orientation. Remember our maxim: Although we find it convenient to talk separately of psychological and biological explanations, everything psychological is simultaneously biological.

The critical questions are, can this finding be replicated? If so, when does the brain difference begin? At conception? In the womb? During childhood or adolescence? Does experience produce the difference? Or do genes or prenatal hormones (or genes via prenatal hormones)?

LeVay does not view this little neural center as a sexual orientation center; rather, he sees it as an important part of the neural pathway engaged in sexual behavior. Moreover, he acknowledges that it’s possible that sexual behavior patterns influence the brain’s anatomy. (In fish, rats, birds, and humans, brain structures are known to vary with experience.) But he believes it more likely that brain anatomy influences sexual orientation.

Laura Allen and Roger Gorski (1992) offered a similar conclusion after discovering that a section of the fibers connecting right and left hemispheres is one-third larger in homosexual men than in heterosexual men. “The emerging neuroanatomical picture,” notes Brian Gladue (1994), “is that, in some brain areas, homosexual men are more likely to have female-typical neuroanatomy than are heterosexual men.”

Genes and Sexual Orientation

The evidence suggests that genetic influence plays a role (Whitam & others, 1993).

One research team studied the twin brothers of homosexual men. Among their identical twin brothers, 52 percent were homosexual, as were 22 percent of fraternal twin brothers (Bailey & Pillard, 1991, 1995).

In a follow-up study of homosexual women, a similar 48 percent of their identical twins were homosexual, as were 16 percent of their fraternal twins (Bailey & others, 1993).

With half the identical twin pairs differing, we know that genes aren’t the whole story. Moreover, a new study using a diverse sample of Australian twins found somewhat lower rates of sexual similarity–although, again, identical twins were more likely than fraternal twins to share homosexual feelings (Bailey & others, 1997).

This is the sort of pattern we expect to see when genes are having an influence. Moreover, with a single transplanted gene, scientists can now cause male fruit flies to display homosexual behavior (Zhang & Odenwald, 1995).

Prenatal Hormones and Sexual Orientation

The elevated rate of similar homosexual orientation even in fraternal twins might also result from their sharing the same prenatal environment. In animals, abnormal prenatal hormone conditions have altered the sexual orientation of a fetus.

German researcher Gunter Dorner (1976, 1988) pioneered this research by manipulating a fetal rat’s exposure to male hormones, thereby “inverting” its sexual behavior toward rats of the other sex. Female sheep will likewise show homosexual behavior if their pregnant mothers are injected with testosterone during a critical gestation period (Money, 1987).

Atypical prenatal hormones may produce similar results in humans. A critical period for the human brain’s neural-hormonal control system may exist between the middle of the second and fifth months after conception (Ellis & Ames, 1987; Gladue, 1990; Meyer-Bahlburg, 1995). It seems that exposure to the hormone levels typically experienced by female fetuses during this time may predispose the person (whether female or male) to be attracted to males in later life.

Some tests reveal that homosexual men have spatial abilities like those typical of heterosexual women–a pattern consistent with the hypothesis that homosexuals were exposed to atypical prenatal hormones (Gladue, 1994; McCormick & Witelson, 1991).

Curiously, gay men also have fingerprint patterns rather like those of heterosexual women. Most people have more fingerprint ridges on their right hand. Jeff Hall and Doreen Kimura (1994) observed that this right-versus-left difference is less true of females and gay males than of heterosexual males–a difference that these researchers believe is due to prenatal hormones.

Because the physiological evidence is preliminary and controversial, some scientists remain skeptical. Rather than specifying sexual orientation, perhaps biological factors predispose a temperament that influences sexuality “in the context of individual learning and experience” (Byne & Parsons, 1993).

Perhaps, theorizes Daryl Bem (1996), genes code for prenatal hormones and brain anatomy, which predispose temperaments that lead children to prefer sex-typical or sex-atypical activities and friends. These preferences may lead children later to feel attracted to whichever sex feels different. Boys with feminine interests may find masculine males exotic. This could explain why, in personal ads, gay men tend to seek masculine partners and lesbians feminine partners (Bailey & others, 1997).

The dissimilar-seeming sex (one’s own, for homosexual people) becomes associated with anxiety and other forms of arousal, which eventually gets transformed into romantic arousal. The exotic becomes erotic.

Regardless of the process, the consistency of the genetic, prenatal, and brain findings has swung the pendulum toward a physiological explanation. Nature more than nurture, most psychiatrists now believe, predisposes sexual orientation (Vreeland & others, 1995). If biological influences prove critical (perhaps especially in certain environmental contexts), it would explain why sexual orientation is so difficult to change.

Still, some people wonder: Should the cause of sexual orientation matter?

Maybe it shouldn’t, but people’s assumptions matter. Those who believe (as most homosexual people believe) that sexual orientation is a biological given–an enduring identity, not a choice–express more accepting attitudes toward homosexual persons (Allen & others, 1996; Furnham & Taylor, 1990; Whitley, 1990).

In American surveys, agreement that homosexuality is “something that people are born with” doubled from 16 to 31 percent between 1983 and 1993. Over roughly the same period, support for equal job rights for homosexuals increased from 59 to 80 percent (Moore, 1993).

Between 1982 and 1996, agreement that “homosexuality should be an acceptable alternative lifestyle” also increased, from 34 to 44 percent (Gallup, 1996). Accepting attitudes are most common among women and those with a gay or lesbian friend or relative (Herek & Capitanio, 1996; Kite & Whitley, 1996).

To gay and lesbian activists, the new biological research is a double-edged sword (Diamond, 1993). If sexual orientation, like skin color and sex, is genetically influenced, that offers a further rationale for civil rights protection. Moreover, it may alleviate parents’ concerns about their children having gay teachers and role models. It does, however, raise the haunting possibility that genetic markers of sexual orientation could someday be identified through fetal testing, and the fetus aborted.

Sex and Human Values

Recognizing that values are both personal and cultural, most sex researchers and educators strive to keep their writings on sexuality value-free. But can the study of sexual behavior and what motivates it really be free of values?

Those who think not say that the very words we use to describe behavior often reflect our personal values. When sex researchers label sexually restrained individuals as “erotophobic” and as having “high sex guilt,” they express their own values.

Whether we label sexual acts we do not practice as “perversions,” “deviations,” or part of an “alternative sexual life-style” depends on our attitudes toward the behaviors. Labels both describe and evaluate.

When education about sex is separated from the context of human values, some students may get the idea that sexual intercourse is merely recreational activity. Diana Baumrind (1982), a University of California child-rearing expert, has observed that adolescents interpret sex education that pretends to be “value-free” as meaning that adults are neutral about adolescent sexual activity. Such an implication is unfortunate, she added, because “promiscuous recreational sex poses certain psychological, social, health, and moral problems that must be faced realistically.”

Researchers have found that teenagers who have had formal sex education are no more likely to engage in premarital sex than those who have not (Furstenberg & others, 1985; Zelnik & Kim, 1982).

Moreover, we enrich our lives by knowing ourselves, by realizing that others share our feelings, by understanding what is likely to please or displease our loved one. Witness the crumbling of falsehoods about homosexuality. Witness the growing realization that some types of sexually explicit material can lead people to devalue or hurt others.

Perhaps we can agree that the knowledge provided by sex research is preferable to ignorance, yet also agree that researchers’ values should be stated openly, enabling us to debate them and to reflect on our own values.

We might also remember that scientific research on sexual motivation does not aim to define the personal meaning of sex in our own lives. One can know every available fact about sex–that the initial spasms of male and female orgasm come at 0.8-second intervals, that the female nipples expand 10 millimeters at the peak of sexual arousal, that systolic blood pressure rises some 60 points and the respiration rate to 40 breaths per minute–but fail to understand the human significance of sexual intimacy.

Surely one significance of sexual intimacy is its expression of our deeply social nature. Sex is a socially significant act. Men and women can achieve orgasm alone, yet most people find greater satisfaction while embracing their loved one. There is a yearning for closeness in sexual motivation. Sex at its human best is life-uniting and love-renewing.

ref: http://www.soulforce.org/article/644

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The Science of Gaydar

January 11, 2012 at 5:50 pm (Sicence)

If sexual orientation is biological, are the traits that make people seem gay innate, too? The new research on everything from voice pitch to hair whorl.

 

1. By David France Published Jun 17, 2007

As a presence in the world—a body hanging from a subway strap or pressed into an elevator, a figure crossing the street—I am neither markedly masculine nor notably effeminate. Nor am I typically perceived as androgynous, not in my uniform of Diesels and boots, not even when I was younger and favored dangling earrings and bright Jack Purcells. But most people immediately read me (correctly) as gay. It takes only a glance to make my truth obvious. I know this from strangers who find gay people offensive enough to elicit a remark—catcalls from cab windows, to use a recent example—as well as from countless casual social engagements in which people easily assume my orientation, no sensitive gaydar necessary. I’m not so much out-of-the-closet as “self-evident,” to use Quentin Crisp’s phrase, although being of a younger generation, I can’t subscribe to his belief that it is a kind of disfigurement requiring lavender hair rinse.

I once placed a personal ad in which I described myself as “gay-acting/gay-appearing,” partly as a jab at my peers who prefer to be thought of as “str8” but mostly because it’s just who I am. Maybe a better way to phrase it would have been “third-sexer,” the category advanced by the gay German sexologist Magnus Hirschfeld 100 years ago. The label fell into disrepute, but lately a number of well-known researchers in the field of sexual orientation have been reviving it based on an extensive new body of research showing that most of us, whether top or bottom, butch or femme, or somewhere in between, share a kind of physical otherness that locates us in our own quadrant of the gender matrix, more like one another than not. Whatever that otherness is seems to come from somewhere deep within us. It mostly defies our efforts to disguise it. That’s what we mean by gaydar—not the skill of the viewer so much as the telltale signs most gay people project, the set of traits that make us unmistakably one.

The late psychologist and sexologist John Money famously called these the details of our “gendermaps,” which he believed are drawn primarily by life’s experience and social conditioning. Money planted some of the earliest flags in the nature-versus-nurture war by claiming that dysfunctional parents, not inborn biology, is what produced “sissy boys,” tomboys, and other gender variants. But today, the pendulum has swung just about as far in the other direction as possible. A small constellation of researchers is specifically analyzing the traits and characteristics that, though more pronounced in some than in others, not only make us gay but also make us appear gay.

At first read, their findings seem like a string of unlinked, esoteric observations. Statistically, for instance, gay men and lesbians have about a 50 percent greater chance of being left-handed or ambidextrous than straight men or women. The relative lengths of our fingers offer another hint: The index fingers of most straight men are shorter than their ring fingers, while for most women they are closer in length, or even reversed in ratio. But some researchers have noted that gay men are likely to have finger-length ratios more in line with those of straight women, and a study of self-described “butch” lesbians showed significantly masculinized ratios. The same goes for the way we hear, the way we process spatial reasoning, and even the ring of our voices. One study, involving tape-recordings of gay and straight men, found that 75 percent of gay men sounded gay to a general audience. It’s unclear what the listeners responded to, whether there is a recognized gay “accent” or vocal quality. And there is no hint as to whether this idiosyncrasy is owed to biology or cultural influences—only that it’s unmistakable. What is there in Rufus Wainwright’s “uninhibited, yearning, ugly-duckling voice,” as the Los Angeles Times wrote a few weeks ago, that we recognize as uniquely gay? Does biology account for Rosie O’Donnell’s crisp trumpet and Charles Nelson Reilly’s gnyuck-gnyuck-gnyuck?

“These are all part and parcel of the idea that being gay is different—that we are different animals to some extent,” says Simon LeVay, the British-born neuroscientist who has dedicated himself to studying these issues. “Hirschfeld was right. I support the idea that we’re a third sex—or a third sex and a fourth sex, gay men and lesbians. Today, there’s scientific documentation behind this.”

Richard Lippa, a psychologist from California State University at Fullerton, is one of the leading cataloguers of the many ways in which gay people are different. I caught up with him a few weeks ago at a booth at the Long Beach Pride Festival in Southern California, where he was researching another hypothesis—that the hair-whorl patterns on gay heads are more likely to go counterclockwise. If true, it will be one more clue to our biological uniqueness.

 

As he recruited experiment subjects, Lippa scanned the passing scalps, some shaved clean, some piled in colorful tresses. “It’s like a kind of art. You look at the back of people’s heads, and it’s literally like a vector field,” he says. “We assume that whatever causes people to be right-handed or left-handed is also causing hair whorl. The theory we’re testing is that there’s a common gene responsible for both.” And that gene might be a marker for sexual orientation. So, as part of his study, he has swabbed the inside cheek of his subjects. It will be months before that DNA testing is complete.

 

 

I was surprised at how many people quickly agreed to lend five minutes of their pride celebration to science. “If I could tell my mother it’s a gene, she would be so happy,” said one, Scott Quesada, 42, who sat in a chair for Lippa’s inspection.

“Classic counterclockwise whorl,” the researcher pronounced, snapping a photo.

Quesada, who is right-handed and seemed to have a typically masculinized finger-length ratio, was impressed. “I didn’t know I had a whorl at all,” he said.

By the end of the two-day festival, Lippa had gathered survey data from more than 50 short-haired men and photographed their pates (women were excluded because their hairstyles, even at the pride festival, were too long for simple determination; crewcuts are the ideal Rorschach, he explains). About 23 percent had counterclockwise hair whorls. In the general population, that figure is 8 percent.

A string of other studies, most of them conducted quietly and with small budgets, has offered up a number of other biological indicators. According to this research, for instance, gay men, like straight women, have an increased density of fingerprint ridges on the thumb and the pinkie of the left hand; and overall their arms, legs, and hands are smaller relative to stature (among whites but not blacks). There are technical differences in the way most men and most women hear, except among lesbians, whose ears function more like men’s. And there are gender-based cognitive differences in which gay men appear more like women. One involves mentally rotating a 3-D object, something males tend to do better than females—except gay men score more like straight women and lesbians function more like straight men. In navigational tasks and verbal-fluency tests, gay men and lesbians tend to have sex-atypical scores.

From these findings, it might be tempting to conclude that lesbians are universally masculinized and gay men are somehow feminized—the classic “inversion model” of homosexuality advanced by Freud. But the picture is more complicated than that. There is also evidence—some more silly-sounding than serious—that homosexuals may be simultaneously more feminine and more masculine, respectively. The stereotypes—that lesbians tend to commit to relationships early and have little interest in casual sex; that gay men have more sexual partners than their counterparts—turn out to be true. One study that supports the hyper-masculinity theory of male homosexuality involves penis size. An Ontario-based psychological researcher named Anthony Bogaert re-sorted Kinsey Institute data—in which 5,000 men answered detailed questions about their sex lives, practices, fantasies, and, it turns out, measurements of their erect organs—along sexual-orientation lines. Gay men’s penises were thicker (4.95 inches versus 4.80) and longer (6.32 inches versus 5.99). The measurements, it should be noted, were self-reported and perhaps involve reporting bias, but no one has done a study investigating whether gay men are more prone to exaggerating their assets, so, well, draw your own conclusions.

But if true, these findings negate the inversion model, Bogaert says. Instead of picturing gender and orientation along a line, with straight men and women on either end and gay people in the middle, he suggests, a matrix might be a more accurate way to map the possibilities.

Some of this work has been derided as modern-day phrenology, and obviously possessing one trait or another—a counterclockwise hair whorl here, an elongated ring finger there—doesn’t necessarily make a person gay or straight. But researchers point out that these are statistical averages from the community as a whole. And the cumulative findings support the belief now widely held in the scientific community that sexual orientation—perhaps along with the characteristics we typically associate with gayness—is biological. “We’re reaching a consensus on a broad question,” says J. Michael Bailey, a psychologist at Northwestern University. Is sexual orientation “something we’re born with or something we largely acquire through social experience? The answer is clear. It’s something we’re born with.”

Because many of these newly identified “gay” traits and characteristics are known to be influenced in utero, researchers think they may be narrowing in on when gayness is set—and identifying its possible triggers. They believe that homosexuality may be the result of some interaction between a pregnant mother and her fetus. Several hypothetical mechanisms have been identified, most pointing to an alteration in the flow of male hormones in the formation of boys and female hormones in the gestation of girls. What causes this? Nobody has any direct evidence one way or another, but a list of suspects includes germs, genes, maternal stress, and even allergy—maybe the mother mounts some immunological response to the fetal hormones.

 

 

Immunological response is the ascendant theory, in fact. We know from a string of surveys that in any family, the second-born son is 33 percent more likely than the first to be gay, and the third is 33 percent more likely than the second, and so on, as though there is some sort of “maternal memory,” similar to the way antibodies are memories of an infection. Perhaps she mounts a more effective immunological response to fetal hormones with each new male fetus. To determine whether the fraternal birth order might also suggest that baby brothers are treated differently in a way that impacts their sexual expression, researchers have studied boys who weren’t raised in their biological families, or who may have been firstborn but grew up as the youngest in Brady Bunch–type homes. In every permutation, the results were the same: What mattered was only how many boys had occupied your mother’s uterus before you.

Some of this research may prove to be significant; some will ultimately get chalked up to coincidence. But the thrust of these developing findings puts activists in a bind and brings gay rights to a major crossroads, perhaps its most significant since the American Psychiatric Association voted to declassify homosexuality as a disease in 1973. If sexual orientation is biological, and we are learning to identify how it happens inside the uterus, doesn’t it suggest a future in which gay people can be prevented? This spring, R. Albert Mohler Jr., the president of a Southern Baptist theological seminary in Kentucky and one of the country’s leading Evangelical voices, advocated just that. “We want to understand why some persons will struggle with that particular sin,” he explained. “If there is a way we can help with the struggle, we should certainly be open to it, the same way we would help alcoholics deal with their temptation.”

That in part is why gay people have not hungered for this breakthrough. Late last year, Martina Navratilova joined activists from PETA to speak out against an experiment that sought to intentionally turn sheep gay (it failed, but another experiment successfully turned ferrets into homosexuals, and the sexual orientations of fruit flies have been switched in laboratories). Some 20,000 angry e-mails clogged the researchers’ inboxes, comparing the work to Nazi eugenics and arguing that it held no promise of any kind to gay people. “There are positives, but many negatives” to this kind of research, says Matt Foreman, executive director of the National Gay and Lesbian Task Force. “I will bet my life that if a quote-unquote cure was found, that the religious right would have no problem with genetic or other kind of prenatal manipulations. People who don’t think that’s a clear and present danger are simply not living in reality.”

 

A study found that 75 percent of gay men sounded gay to a general audience. Were they responding to a recognized gay “accent”?

 

At the dawn of gay politics a half-century ago, the government treated gay people as a menace to national security, and much of the public, kept from any ordinary depictions of gay life, lived in terror of encountering one of us. It was routine, and reliably successful, for defendants in murder cases to prevail by alleging they were fending off a gay assault. (If confronted by the pathology of homosexuality, jurors believed, force was not only appropriate but utterly forgivable.) Back then, many psychiatrists treated homosexuality with shock therapy, detention, or a mind-twisting intervention called “aversion therapy”—a practice that was still in vogue in the late seventies, when a lumpy-faced psychiatrist put me through a regimen of staring at Playboy centerfolds.

The groundwork for change began when Evelyn Hooker, a UCLA psychologist, was approached by a gay former student in the fifties. He had noticed that all research on homosexuals looked at men and women who were imprisoned or institutionalized, thereby advancing the belief that homosexuals were abnormal. He proposed that she study men like him as a counterpoint. Over the next two decades, she did just that, proving that none of the known psychological screens could detect a healthy gay person—that there was no clinical pathology to sexual orientation. Of necessity, research at the time was focused on demonstrating how unremarkable gay men and lesbians are: indistinguishable on all personality inventories, equally good at all jobs, benign as parents, unthreatening as neighbors, and so on. On the strength of Hooker’s findings, and a Gandhian effort by activists, the APA changed its view on homosexuals 34 years ago.

Thereafter, the field of sexual-orientation research fell dormant until 1991, when Simon LeVay conducted the very first study of homosexual biological uniqueness. He had been a researcher at the Salk Institute in La Jolla, California, when his lover fell ill with AIDS. He took a year off to care for him, but his partner ultimately died. Returning to work, LeVay decided he wanted to concentrate on gay themes. “Just like a lot of gay people who’d been directly affected by the epidemic, I felt a desire to do something more relevant to my identity as a gay man,” says LeVay. “Some people have said I was out to try and prove that it wasn’t my fault that I was gay. I reject that. In my case, since neuroscience was my work, that just seemed like the way to go.

 

Ironically, AIDS had also given LeVay opportunity. Before the epidemic, cadavers available for dissecting came with scant personal background besides age and cause of death. But because AIDS was still largely a gay disease, it was possible for the first time to do detailed neuroanatomical studies on the bodies of known gay men. (Being lucky enough to have no proprietary cause of death, lesbians were excluded from the study.)

LeVay decided to make the first detailed comparison of the brain’s hypothalamus, a small region at the base of the brain responsible for regulating everything from blood pressure and body temperature to hunger and wake-sleep cycles. And because it’s awash in more hormones than any other part of the brain, it also helps control emotions and sex drive and enjoys a reputation among neurologists, as LeVay noted in his book The Sexual Brain, for being “haunted by animal spirits and the ghosts of primal urges.”

LeVay suspected the secret to sexual orientation might lurk there as well. It was already known that in (presumably straight) men, a cell cluster in the hypothalamus called INAH3 is more than twice the size of the cluster in (presumably straight) women, a distinction probably created during fetal development when male hormones begin acting on boy fetuses and the two genders embark on different biological courses. LeVay designed a study to see if there were any size differences inside gay brains. His results were startling and unexpected. In gay men, INAH3 is similar in size to straight women’s.

This finding challenged a lot of what scientists believed. “The brain was considered pretty hardwired,” says Roger Gorski, a neurobiologist at UCLA who researches sexual differentiation. “It was male or female, period. Then Simon’s study shows that there could be intermediates. That wasn’t just a watershed—it pushed the water over the waterfall.”

At the time, LeVay presented his findings with caution, acknowledging that HIV or AIDS medications might have been responsible for altering brain structure. But more recently, an important study of sheep brains has replicated his findings. Sheep are among 500 animal species where homosexuality has been documented. They are also among the few who practice exclusive homosexuality, like many humans. In any population of sheep, about 8 percent of males show exclusive homosexual behavior. Little is known about the romantic life of Sapphic sheep because ewes tend to express their sexual interests by standing entirely still, yielding no clues about their partner preferences.

Slicing open the brains of ten ewes, eight female-oriented rams, and nine males who preferred other rams, researchers in the Oregon Health and Science University School of Medicine found nearly the same variations in hypothalamus that LeVay first noticed. Male sheep who were attracted to females had a significantly larger hypothalamus dimension than females or male-oriented males.

A second study in humans also found size differences, though less dramatic, in the hypothalamus cluster identified by LeVay. “There’s now more reason to think my results are right, that the gay brain has this distinction,” he says.

If LeVay’s research suggested that biology—not environment, vice, or sinfulness—was likely responsible for male homosexuality, the geneticist Dean Hamer, an author and molecular biologist at the National Institutes of Health, hoped to pinpoint the exact biological mechanism responsible. He scanned gene groups in pairs of gay siblings looking for sites where the relatives had inherited the same DNA more frequently than would be expected on the basis of chance. In 1993, he located a region in the human genome, called Xq28, that appeared to be associated with gayness, a finding that has generated some controversy among researchers who have not fully confirmed the results.

A large-scale study within the next year is expected to determine more conclusively if a gene (or genes) is linked to sexual orientation. Alan R. Sanders, a psychiatrist from Northwestern University, is enrolling 1,000 pairs of gay brothers in one of the largest sexual-orientation studies ever undertaken. With the experiment, funded by an NIH grant of over $1 million, Sanders will attempt to map genes that influence sexual orientation.

Why has it taken fourteen years to carry out such an investigation? Hamer says there is very little research money, and almost no glory, to be gained in the hunt for gayness. “At about the same time as Xq28 came out, we found another gene involved in anxiety—the target gene for Prozac, and since that time, there have been now almost 800 peer-reviewed publications on that gene. Whereas for the gay gene, every experiment has been done by three or four students, most of them my students.”

One of the riddles still vexing geneticists is why only 50 percent of gay identical twins share a sexual orientation with their sibling, despite being genetically identical. “We know from all sorts of research that it’s not your upbringing, not relationship with parents or siblings, not early-childhood sexual experiences and whether you go to a Catholic school or not,” says Sven Bocklandt, a geneticist at UCLA. “What I believe is that it is the ‘epigenetics environment,’ meaning the environment on top of our DNA—meaning the way that the gene is regulated. If you have identical twins, the genes are identical, but they are used differently. Every man and every woman has all the genes to make a vagina and womb and penis and testicles. In the same way, arguably, every man and woman has the genetic code for the brain networks that make you attracted to men and to women. You activate one or the other—and if you activate the wrong one, you’re gay.”

I can’t ignore Bocklandt’s use of the word wrong in relation to gay genetic codes. I don’t believe Bocklandt has any agenda in his work beyond scientific exploration, nor do I have any reason to believe he is anti-gay. Rather, Bocklandt is driven, as he likes to say, by a voracious curiosity about all sorts of sexual orientations. “This is not about a gay gene,” he says. “This is about sexual attraction, and about love. And about why crocodiles mate and why pigeons mate. It’s amazing to me that we don’t understand how that works. It’s so fundamental. Life on Earth would be very different if heterosexuality didn’t exist. That’s what we’re trying to figure out.”

But every discovery in this field ignites a new discussion of morality. Politically, there is something very powerful about the notion that sexual orientation is a matter of biology, not choice. In poll after poll, of the one third of Americans who believe homosexuality is socially influenced, in other words “a choice,” about 70 percent think being gay is “not acceptable.” But for those who believe it is biologically mandated, the statistic reverses, and four out of five Americans find gayness “acceptable.”

As Bocklandt’s slip of the tongue illustrates, subtle judgments abound in the field. It is true that homosexuality does not make a whole lot of sense biologically. It lacks an obvious purpose. That’s the reason evolution-theory scholars call it “maladaptive” and radio shock jock Laura Schlessinger labeled it a “biological error.” But Stanford biology professor Joan Roughgarden points out in her book Evolution’s Rainbow that most homosexual activity in the animal kingdom serves a fundamentally social purpose. Japanese macaques, for instance, live in female-only societies, arranged in rigid hierarchies. Power and cohesion are established through lesbian couplings, which can last up to four days and seem to prevent violence and aggression. Among many species, in fact, gayness seems to facilitate complex societies. One species of bird has males, females, and “marriage brokers” of a third gender, there to keep the species perpetuating. As adolescents, male bottlenose dolphins perform a kind of oral sex on one another—or in threesomes or foursomes—in rituals that create lifelong friendships and defense partnerships against sharks and other predators.

 

If we identify how sexual orientation is set in utero, doesn’t that suggest a future in which gay people can be prevented?

 

But for most in the animal kingdom, same-sex pairing is either fleeting or situational. Even Silo and Roy, for six years the poster-penguins for same-sex love in the Central Park Zoo—they famously raised a daughter together—were not destined to last forever. Silo waddled off with a female named Scrappy in 2005, says zoo director Dan Wharton, adding that we shouldn’t worry about Roy’s hurt feelings. “Penguins are matter-of-fact about these things.”

That still leaves a million questions about those gay rams and humans like me, who fall on the far edge of Alfred Kinsey’s sexual-orientation scale, exclusively gay. In a universe in which we look for purpose in order to appoint value, what is the purpose of my gayness?

Dean Hamer sees one possible answer in the fraternal-birth-order studies. “In Polynesian cultures, where you’re talking about very big families, it was typical to have the last-born son be mahu, or gay,” he says. Explorers described young boys who looked after the family and sometimes dressed as girls. “They suspected that their families had made them that way. But you just can’t take a guy and make him clean up and have him become gay. He’s got to have some gayness inside. Maybe that’s the biological purpose to the mahu: taking care of Mom.”

He says this half in jest, I think, but some other evidence bolsters his argument, including the appearance of transgender younger sons among Native Americans (the so-called two-spirits) and in premodern corners of India, Samoa, and Indonesia. A survey published this year suggested that transgender fa’afafines in Samoa are more “avuncular” than heterosexuals—that is, more likely to care for kin. Another study says that female relatives of gay men may have more children; perhaps the very thing that makes their brothers and sons gay makes them more fertile, an ideal situation with extra babysitters on hand. You can slice this stuff any way you want.

Fewer studies have focused specifically on lesbians, perhaps because AIDS didn’t provide the same urgent impetus for studying female sexuality. But the research that has been conducted has yielded some interesting, though decidedly cloudy, results. According to some studies, lesbians are more likely to have homosexual relatives than nonlesbians. They also have notably longer bone growth in their arms, legs, and hands, hinting that they had greater androgen exposure during development, according to James Martin, a physiologist with Western University of Health Sciences in Pomona, California. Another indicator comes in a 2003 study in the journal Behavioral Neuroscience that measured something called “prepulse inhibition,” which is the part of our startle mechanism that’s believed to defy practice or training—something hardwired, in other words. Men tend to blink less than women in such experiments; gay and heterosexual men had similar responses, but lesbians, it turns out, were more like men than not.

In many other studies, though, lesbians have appeared less unique than gay men, leading some people to wonder if their sexual orientation is innate. Michael Bailey—who, as a heterosexual researcher, is a minority in this field—even doubts the existence of female sexual orientation, if by orientation we mean a fundamental drive that defies our conscious choices. He bases this provocative gambit on a sexual-arousal study he and his students conducted. When shown pornographic videos, men have an undeniable response either to gay or straight images but not both, according to sensitive gauges attached to their genitals—it’s that binary. Female sexual response is more democratic, opaque, and unpredictable: Arousal itself is harder to track, and there is evidence that it defies easy categorization. “I don’t yet understand female partner choices very well, and neither does anyone else,” Bailey wrote me in an e-mail. “What I do think it’s time to do is admit that female sexuality looks in some ways very different from male sexuality, and that there is no clear analog in women of men’s directed sexual-arousal pattern, which I think is their sexual orientation. I am not sure that women don’t have a sexual orientation, but it is certainly unclear that they do.”

He contends that what they have instead is sexual preference—they might prefer sex with women, but something in their brains can still sizzle at the thought of men. Many feminist scholars agree with this assessment, and consider sexuality more of a fluid than an either-or proposition, but some don’t. “I think women do have orientations, but they don’t circumscribe the range of desires that women can experience to the same degree as men,” says Lisa Diamond, a psychology professor at the University of Utah, who is writing a book on the subject. “For women, there’s more wiggle room. You can think of orientation as defining a range of possible responses, and for women, it’s much broader.”

Bailey stops short of saying that lesbianism is a myth (although he has notoriously declared that true male bisexuality doesn’t exist and dismissed many transgender people as peculiar sexual fetishists, drawing lasting enmity from gay and trans groups). But it may be less hard-wired. And it appears to have separate triggers and correlates that haven’t been identified yet. In studies of twins, there is a lower correlation of sexual orientation between female siblings than male siblings, for instance. “We’re at a place,” agrees Diamond, “where everyone agrees that whatever is going on is quite distinct between the sexes.”

I suppose the main upside to this kind of work, besides any impact it might have on securing gay rights, is the comfort of self-knowledge. The secrets lurking in the hypothalamus (and the ring finger and the hair whorl) aren’t just about who we desire but about a more fundamental organization of our personalities, individually and collectively. Still, some have dismissed all this field-guide work as wrongheaded. Gaydar can no more be proved than a sixth sense, they say. What’s being classified as fundamentally gay is nothing more than cultural signals that vary so much from one part of the world to another that they’re worthless as clues to anything. It is surely true that gaydar has its blind spots. When I traveled through Nigeria a few years ago, I was unable after nearly a month to say with any conviction that I had encountered any gay people along my way. No knowing eye contact, no species recognition. (Then again, it’s not as if I was able to measure index-to-ring finger ratios.)

Where were they all? In Lagos, the morning newspaper offered an answer. According to a tiny news squib, a court had just convicted a young man of sodomy and sentenced him to death by stoning. Two other death sentences were handed down to gay people in the few days before I boarded my airplane. I paid a visit to one of the top human-rights agencies in the country and asked why they weren’t protesting these cases. The director looked at me dumbstruck. “Because sodomy,” he said as if speaking to a child, “is illegal.” To survive, they were hiding, even from me—they had edited down their gendermaps to the barest minimum and disappeared.

Still, Dr. Lippa, the hair-whorl researcher, is publishing a paper in the Archives of Sexual Behavior later this year that seems to prove the existence of gay-typical behavior across the globe. Lippa is looking at a 2005 BBC Internet survey, part of a BBC documentary project called Secrets of the Sexes, which included more than 200,000 respondents in 53 countries answering questions about everything from their occupational interests to their sexual histories and personalities. Lippa, a tall and slender man who came out to his parents in his thirties, analyzed the data first along gender lines, then compared straight people to gay people. What he found, he says, is a cross-cultural confirmation of what amount to stereotypes.

“It probably comes as no shock to you that on average men say they’re interested in being mechanics, or electrical engineers, or construction workers, whereas on average women are more interested in, say, being an interior decorator or a social worker or an artist,” he tells me. “Similarly, the differences between gay men and straight men are pretty large. On average, gay men are interested more in what you would consider female-typical occupations and hobbies than straight men. Same with women. It’s not universal. Some gay men like football games and like working on cars and are electrical engineers. But a large majority answer this way.”

It could be that his study says more about the limited number of vocations where gay men feel comfortable expressing themselves, and we might be equally drawn to construction sites if we thought we might be accepted there. It could be that the study says as much about the globalization of culture as the biological nature of gayness.

Even Lippa hesitates to say that gay people are essentially different from straight. “Essentialism,” he explains, “is the enemy of a lot of academics,” because it shuts down inquiry into all the possible influences. Perhaps there are a dozen possible routes to homosexuality, any combination of which might produce a number of the traits being catalogued now. It might be that there is no single thing called homosexuality—that there are instead dozens of homosexualities, scores of potential outcomes in terms of personality, and endless potentials for describing them. “For example, do gay men who have older brothers show more or less feminine? Do gay men with counterclockwise hair have more masculine traits? One cause might create a more feminine homosexuality than another.

Of course, biology doesn’t determine everything. And some critics of sexual-orientation researchers blame them for minimizing the role of experience in determining our affectional course in life. The feminist biologist Anne Fausto-Sterling has waged a constant battle against their research, which she calls “a big house of cards” that ignores the power of environment in creating personality. Nurture, she argues, can and should be studied as a link to sexual orientation. The baby penguin raised by her two dads is a potential case study—though genetically unrelated to either parent, in the last few mating seasons she has mated with another female.

The rush to declare a biological mandate is motivated by a political agenda, says Fausto-Sterling, the author of Sexing the Body, who is married to a woman after a marriage to a man. “For me and for any feminist, I think it’s a pretty fragile way to argue for human rights. I want to see the claims for gay rights made on moral, ethical, legal, and constitutional bases that don’t rely on a particular scientific view of sexual development.”

Especially if that view invites the opponents of gay people to consider dramatic interventions meant to stop the development of homosexual orientation in a fetus. What if prenatal tests were able to show a predisposition to gayness? How long would it be before some pharmaceutical company develops a patch to regulate hormone flow and direct the baby’s orientation? Michael Bailey, for one, isn’t troubled by the moral implications any more than he would oppose fetal screens for potential birth defects, though he quickly adds his personal belief that homosexuality is “a good” on par with heterosexuality. “There’s no reason to ban, or become hysterical about, selecting for heterosexuality,” he says. “That’s precisely what parenting is about: shaping the children to have traits the parents value.”

It’s bizarre to think some value systems might lump gayness in with—say—sickle-cell anemia or Down syndrome. As Matt Foreman from the Task Force put it, “It’s not playing with the number of toes you have; it’s really manipulating your very essence. So many people see gay people only in terms of sexual behavior, as opposed to what sexual orientation is really about, which is how you fit into the world. I don’t want to get mushy, but it’s about your soul.”

ref: http://nymag.com/news/features/33520/

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What The Science Says…

January 11, 2012 at 5:40 pm (Sicence)

what the science says

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Gay brothers may hold genetic clues

November 15, 2011 at 11:36 am (Sicence)

 

M. Spencer Green  /  AP file

Julio Cabrera, a student at DePaul University in Chicago, is participating in a study of 1,000 pairs of gay brothers. Researchers are looking for genetic clues to the origin of homosexuality.

CHICAGO — Julio and Mauricio Cabrera are gay brothers who are convinced their sexual orientation is as deeply rooted as their Mexican ancestry.

They are among 1,000 pairs of gay brothers taking part in the largest study to date seeking genes that may influence whether people are gay. The Cabreras hope the findings will help silence critics who say homosexuality is an immoral choice.

If fresh evidence is found suggesting genes are involved, perhaps homosexuality will be viewed as no different than other genetic traits like height and hair color, said Julio, a student at DePaul University in Chicago.

Adds his brother, “I think it would help a lot of folks understand us better.”

The federally funded study, led by Chicago area researchers, will rely on blood or saliva samples to help scientists search for genetic clues to the origins of homosexuality. Parents and straight brothers also are being recruited.

While initial results aren’t expected until next year — and won’t provide a final answer — skeptics are already attacking the methods and disputing the presumed results.

Previous studies have shown that sexual orientation tends to cluster in families, though that doesn’t prove genetics is involved. Extended families may share similar child-rearing practices, religion and other beliefs that could also influence sexual orientation.

Research involving identical twins, often used to study genetics since they share the same DNA, has had mixed results.

One widely cited study in the 1990s found that if one member of a pair of identical twins was gay, the other had a 52 percent chance of being gay. In contrast, the result for pairs of non-twin brothers, was 9 percent. A 2000 study of Australian identical twins found a much lower chance.

No single ‘gay gene’
Dr. Alan Sanders of Evanston Northwestern Healthcare Research Institute, the lead researcher of the new study, said he suspects there isn’t one so-called “gay gene.”

It is more likely there are several genes that interact with nongenetic factors, including psychological and social influences, to determine sexual orientation, said Sanders, a psychiatrist.

Still, he said, “If there’s one gene that makes a sizable contribution, we have a pretty good chance” of finding it.

Many gays fear that if gay genes are identified, it could result in discrimination, prenatal testing and even abortions to eliminate homosexuals, said Joel Ginsberg of the Gay and Lesbian Medical Association.

However, he added, “If we confirm that sexual orientation is an immutable characteristic, we are much more likely to get the courts to rule against discrimination.”

Orlin Wagner  /  AP file

Mauricio Cabrera, photographed at his home in Olathe, Kan., is, along with his brother, Julio, participating in the study. Both are convinced their sexual orientation is as deeply rooted as their Mexican heritage, and they hope new research will help silence critics who say homosexuality is an immoral choice.

There is less research on lesbians, Sanders said, although some studies suggest that male and female sexual orientation may have different genetic influences.

His new research is an attempt to duplicate and expand on a study published in 1993 involving 40 pairs of gay brothers. That hotly debated study, wrongly touted as locating “the gay gene,” found that gay brothers shared genetic markers in a region on the X chromosome, which men inherit from their mothers.

That implies that any genes influencing sexual orientation lie somewhere in that region.

Previous attempts to duplicate those results failed. But Sanders said that with so many participants, his study has a better chance of finding the same markers and perhaps others on different chromosomes.

If these markers appear in gay brothers but not their straight brothers or parents, that would suggest a link to sexual orientation. The study is designed to find genetic markers, not to explain any genetic role in behavior.

And Sanders said even if he finds no evidence, that won’t mean genetics play no role; it may simply mean that individual genes have a smaller effect.

Skeptics include Stanton Jones, a psychology professor and provost at Wheaton College in Wheaton, Ill. An evangelical Christian, Jones last month announced results of a study he co-authored that says it’s possible for gays to “convert” — changing their sexual orientation without harm.

Jones said his results suggest biology plays only a minor role in sexual orientation, and that researchers seeking genetic clues generally have a pro-gay agenda that will produce biased results.

Sanders disputed that criticism.

“We do not have a predetermined point we are trying to prove,” he said. “We are trying to pry some of nature’s secrets loose with respect to a fundamental human trait.”

Jones acknowledged that he’s not a neutral observer. His study involved 98 gays “seeking help” from Exodus International, a Christian group that believes homosexuals can become straight through prayer and counseling. Exodus International funded Jones’ study.

The group’s president, Alan Chambers, said he is a former homosexual who went straight and believes homosexuality is morally wrong.

Critics espouse ‘freedom to choose’
Even if research ultimately shows that genetics play a bigger role, it “will never be something that forces people to behave in a certain way,” Chambers said. “We all have the freedom to choose.”

The Cabrera brothers grew up in Mexico in a culture where “being gay was an embarrassment,” especially for their father, said Mauricio, 41, a car dealership employee from Olathe, Kan.

They had cousins who were gay, but Mauricio said he still felt he had to hide his sexual orientation and he struggled with his “double life.” Julio said having an older brother who was gay made it easier for him to accept his sexuality.

Jim Larkin, 54, a gay journalist in Flint, Mich., said the genetics study is a move in the right direction.

Given the difficulties of being gay in a predominantly straight society, homosexuality “is not a choice someone would make in life,” said Larkin, who is not a study participant.

He had two brothers who were gay. One died from AIDS; the other committed suicide. Larkin said he didn’t come out until he was 26.

“I fought and I prayed and I went to Mass and I said the rosary,” Larkin said. “I moved away from everybody I knew … thinking maybe this will cause the feelings to subside. It doesn’t.”

ref: http://www.msnbc.msn.com/id/21309724/ns/health-health_care/t/gay-brothers-may-hold-genetic-clues/#.TsFBaWD59O0

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BORN OR BRED? – Article

November 15, 2011 at 11:32 am (Sicence)

Science Does Not Support the Claim

That Homosexuality Is Genetic

By Robert Knight

The debate over homosexual “marriage” often becomes focused on whether homosexuality is a

learned behavior or a genetic trait. Many homosexual activists insist that “science” has shown

that homosexuality is inborn, cannot be changed, and that therefore they should have the “right

to marry” each other.

Beginning in the early 1990s, activists began arguing that scientific research has proven that

homosexuality has a genetic or hormonal cause. A handful of studies, none of them replicated

and all exposed as methodologically unsound or misrepresented, have linked sexual orientation

to everything from differences in portions of the brain,1,2 to genes,3 finger length,4 inner ear

differences,5 eye-blinking,6 and “neuro-hormonal differentiation.”7

Meanwhile, Columbia University Professor of Psychiatry Dr. Robert Spitzer, who was

instrumental in removing homosexuality in 1973 from the American Psychiatric Association’s

list of mental disorders, wrote a study published in the October 2003 Archives of Sexual

Behavior. He contended that people can change their “sexual orientation” from homosexual to

1 D.F. Swaab and M.A. Hofman, Brain Res. 537 (1990): 141-48, as cited in Dennis McFadden and E.G. Pasanen, “Comparisons

of the auditory systems of heterosexuals and homosexuals: Click-evoked otoacoustic emissions,” Proceedings of the National.

Academy of Science USA 95 (March 1998): 2709-13.

2 Simon LeVay, “A Difference in Hypothalamic Structure Between Heterosexual and Homosexual Men,” Science Vol. 253

(1991): 1034-37.

3 D.H. Hamer, S. Hu, V.L. Magnuson, N. Hu and A.M.L. Pattatucci, Science 261(1993): 321-27, as cited in McFadden.

4 B.J. Sigesmund, “Let Your Fingers Do the Talking,” Newsweek “Web Exclusive,” 31 March 2000.

5 McFadden and Pasanen.

6 “Sexual orientation ‘hard-wired’ before birth – startling new evidence revealed in the blink of an eye,” press release, University

of East London (UEL), England, October 2, 2003, reporting on findings by the UEL’s Dr. Qazi Rahman, along with the Institute

of Psychiatry’s Dr. Veena Kumari and Dr. Glenn Wilson. In terms of eye-blink reactions to sudden loud noises, “The team

discovered significant differences in the response between male and female, and heterosexual and homosexual subjects.”

Rahman: “The startle response is pre-conscious and cannot be learned.”

7 Qazi Rahman, “Comments on the Neuroanatomy of Human Sexual Orientation and Proposed Neuroendocrine Hypotheses,”

Contemporary Neurology (1999): Number 2A: http://mitpress.mit.edu/jrnls-catalog/cont-neuro.html.

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heterosexual.8 Spitzer interviewed more than 200 people, most of whom claimed that through

reparative therapy counseling, their desires for same-sex partners either diminished significantly

or they changed over to heterosexual orientation. Although still a proponent of homosexual

activism, Spitzer has been attacked unmercifully by former admirers for this breach of the

ideology that people are “born gay and can’t change.” Immutability is a central tenet of

demands for “gay rights” and “gay marriage.”

Because no single study can be regarded as definitive, more research on people who have

overcome homosexuality needs to be done. But a considerable body of previous literature about

change from homosexuality to heterosexuality has been compiled, and the sheer number of

exceptions to the “born gay” theory should be a warning to researchers and media to proceed

with caution before declaring that science has “proved” that homosexuality is genetic.9

Other recent developments also suggest that homosexuality is not genetically determined. The

Washington Post reported that bisexuality is fashionable among many young teen girls, who go

back and forth from being “straight” to “gay” to “bi” to “straight” again.10

Post reporter Laura Sessions Stepp writes:

Recent studies among women suggest that female homosexuality may be grounded more

in social interaction, may present itself as an emotional attraction in addition to or in

place of a physical one, and may change over time.11

She cites one such study by Lisa M. Diamond, assistant professor of psychology and gender

studies at the University of Utah, who in 1994 began studying a group of females aged 16 to 23

who were attracted to other females.12 Over the course of the study, “almost two-thirds have

changed labels,” Stepp reports.

Against increasing evidence that homosexual behavior is neither inevitable nor impossible to

resist, a number of studies have been widely publicized as “proof” of a genetic component. But

they are either poorly constructed or misreported as to their significance.

In 1993, Columbia University psychiatry professors Drs. William Byne and Bruce Parsons

examined the most prominent “gay gene” studies on brain structure and on identical twins, and

published the results in the Archives of General Psychiatry. They found numerous

methodological flaws in all of the studies, and concluded that:

8 Robert L. Spitzer, “Can Some Gay Men and Lesbians Change Their Sexual Orientation?”, Archives of Sexual

Behavior, Vol. 32, No. 5, October 2003: 403-417.

9 See, for instance, Charles Socarides, A Freedom Too Far: A Psychoanalyst Answers 1,000 Questions About Causes and Cure

and the Impact of the Gay Rights Movement on American Society (Phoenix, Arizona: Adam Margrave Books, 1996), pp. 115-

155, particularly pp. 151-152.

10 Laura Sessions Stepp, “Partway Gay? For Some Teen Girls, Sexual Preference Is a Shifting Concept,” The Washington Post,

January 4, 2004, p. D-1.

11 Ibid.

12 Lisa M. Diamond, “Was it a phase? Young women’s relinquishment of lesbian/bisexual identities over a 5-year period,”

Journal of Personality & Social Psychology (in press as of 2004).

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There is no evidence at present to substantiate a biologic theory. … [T]he appeal of

current biologic explanations for sexual orientation may derive more from dissatisfaction

with the present status of psychosocial explanations than from a substantiating body of

experimental data.13

After he was roundly attacked by homosexual activists, who accused him of providing

ammunition for conservatives to challenge the gay rights/civil rights comparison based on

immutability, Byne denounced the “false dichotomy: Biology or Choice?” and stated that he was

also skeptical of environmental theories of sexual orientation. He wrote: “There is no compelling

evidence to support any singular psychosocial explanation,” and that he would never “imply that

one consciously decides one’s sexual orientation.”14 But the fact remains that Dr. Byne has

poked gaping holes in the most influential studies purporting to prove that homosexuality is

inborn.

In May 2000, the American Psychiatric Association issued a Fact Sheet, “Gay, Lesbian and

Bisexual Issues,” which includes this statement:

“Currently, there is a renewed interest in searching for biological etiologies for homosexuality.

However, to date there are no replicated scientific studies supporting any specific biological

etiology for homosexuality.”

Beyond the false comfort that homosexuals need not seek to alter their behavior in any way,

there may be another motive behind the release and enthusiastic reporting of these studies:

political advantage. As Natalie Angier wrote in The New York Times on September 1, 1991:

[P]roof of an inborn difference between gay and heterosexual men could provide further

ammunition in the battle against discrimination. If homosexuality were viewed legally as

a biological phenomenon, rather than a fuzzier matter of “choice” or “preference,” then

gay people could no more rightfully be kept out of the military, a housing complex or a

teaching job than could, say blacks.15

Simon LeVay, whose brain study in 1991 “jumped from the pages of the periodical Science to

The New York Times and Time, then to CNN and Nightline, and from there to the dinner tables

and offices of the country,” according to writer Chandler Burr, was quite open in his assessment

of the possible impact of his work. “[P]eople who think gays and lesbians are born that way are

also more likely to support gay rights.”16

13 William Byne and Bruce Parsons, “Human Sexual Orientation: The Biologic Theories Reappraised,” Archives of General

Psychiatry, Vol. 50, March 1993: 228-239.

14 Letter from William Byne to Dean Hamer, 2 July 1993, as quoted in Chandler Burr, A Separate Creation: The Search for the

Biological Origins of Sexual Orientation (New York, New York: Hyperion, 1996), p. 81.

15 Natalie Angier, quoted in Charles W. Socarides, “A Freedom Too Far,” (Phoenix, Arizona: Adam Margrave Books, 1995), p.

94.

16 Simon LeVay, quoted in A. Dean Byrd, Ph.D., Shirley E. Cox, Ph.D., and Jeffrey W. Robinson, Ph.D., “The Innate-Immutable

Argument Finds No Basis in Science,” 2002, the National Association for the Research and Therapy of Homosexuality,

http://www.narth.com/docs/innate.html.

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In his book Homosexuality and the Politics of Truth, Dr. Jeffrey Satinover writes:

We will see later the falsity of activists’ repeated assertions that homosexuality is

immutable. They seek to create the impression that science has settled these questions,

but it most certainly has not. Instead, the changes that have occurred in both public and

professional opinion have resulted from politics, pressure, and public relations.17

Despite critical examination, as well as comments by the studies’ own authors that the “gay”

research has been distorted or exaggerated, some of the studies are often cited as “proof” that

“gays are born that way.” A few other studies have arisen in more recent years with as many

flaws or have been misreported in similar fashion. Here is a brief overview of some of the

studies:

UCLA’s Study on Genes and Mice Brains

In October 2003, the journal Molecular Brain Research published a study by UCLA researchers

indicating that sexual identity is genetic.18 Reuters reported it this way: “Sexual identity is wired

into the genes, which discounts the concept that homosexuality and transgender sexuality are a

choice, California researchers reported.”19 A number of other media outlets picked up on this

theme, creating the impression that this study was yet one more piece of evidence for a genetic

theory of homosexuality.

The trouble is, the study doesn’t say anything about homosexuality. All it does is support a

widely accepted theory about hormones and gender. Here is Princeton Professor Dr. Jeffrey

Satinover’s assessment:

The research is a decent piece of basic science and confirms what geneticists have long

known must be the case: That the hormonal milieu that causes sexual differentiation

between males and females is itself determined by genes, in mice as in men. This comes

as no surprise.

But this research says absolutely nothing about homosexuality or transsexualism and any

who claim it does are either ill-informed about genetics, or if not, are deliberately abusing

their scientific knowledge and or credentials in the service of politics – in precisely the

same way that Soviet-era geneticists such as Lysenko did – either in the naïve hope that

distortion of the truth can produce a better society or out of fear for their career prospects.

In either case they should be roundly rebuked for doing so.20

17 Jeffrey Satinover, M.D., Homosexuality and the Politics of Truth (Grand Rapids, Michigan: Hamewith Books, Baker Books,

1996), p. 38.

18 Phoebe Dewing, Tao Shi, Steve Horvath and Eric Vilain, “Sexually dimorphic gene expression in mouse brain precedes

gonadal differentiation,” Molecular Brain Research, Vol. 118, Issues 1-2, 21 October 2003: 82-90.

19 Reuters, “Study says sexual identity is genetic,” 20 October 2003.

20 E-mail correspondence, 21 October 2003.

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The Hypothalamus

The first widely publicized claim for a “gay gene” came in 1991 when Salk Institute researcher

Dr. Simon LeVay published a study in the journal Science noting a difference in a brain structure

called the hypothalamus when evaluating 35 men – 19 homosexuals and 16 heterosexuals.21

LeVay found that the hypothalamus was generally larger in heterosexual men than in

homosexual men. He concluded that the findings “suggest that sexual orientation has a biologic

substrate.”22

The media splashed the study on front pages and TV and radio broadcasts from coast to coast,

despite the fact that LeVay himself cautioned:

“It’s important to stress what I didn’t find. I did not prove that homosexuality is genetic, or find a

genetic cause for being gay. I didn’t show that gay men are born that way, the most common

mistake people make in interpreting my work. Nor did I locate a gay center in the brain. …Since

I looked at adult brains, we don’t know if the differences I found were there at birth, or if they

appeared later.”23

The study also had major problems, which LeVay himself readily admits. First, all 19 of his

homosexual subjects died of complications associated with AIDS. The difference in the

hypothalamus might have been caused by chemical changes in the brain as a response to AIDS.

Dr. Byne argued in Scientific American that “[LeVay’s] inclusion of a few brains from

heterosexual men with AIDS did not adequately address the fact that at the time of death

virtually all men with AIDS have decreased testosterone levels as the result of the disease itself

or the side effects of particular treatments. … Thus it is possible that the effects on the size of

the INAH3 [hypothalamus] that he attributed to sexual orientation were actually caused by the

hormonal abnormalities associated with AIDS.”24

In addition, six of the “heterosexual” men died of AIDS. LeVay admitted later that he didn’t

actually know whether the subjects in his heterosexual sample were, indeed, heterosexual; all of

these subjects were simply “presumed heterosexual.” Given that very few straight men in San

Francisco were contracting AIDS at the time (and still aren’t), this was a wildly unscientific

assumption.

Another weakness of LeVay’s study is that his sample included major “exceptions.” Three of the

homosexuals had larger clusters of neurons than the mean size for the heterosexuals, and three of

the heterosexuals had clusters smaller than the mean size for the homosexuals. LeVay

21 LeVay, op cit.

22 Ibid.

23 Quoted in David Nimmons, “Sex and the Brain,” Discover, Vol. 5, No. 3 (March 1994): 64-71 and cited in A. Dean

Byrd, Ph.D., Shirley E. Cox, Ph.D., and Jeffrey W. Robinson, Ph.D., “The Innate-Immutable Argument Finds No Basis in

Science,” National Association of Research and Therapy for Homosexuality Web site,

http://www.narth.com/docs/innate.html, downloaded 12 January 2004.

24 E. Byne, “The Biological Evidence Challenged,” Scientific American (May 1994): 50-5.

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acknowleged that these exceptions “hint at the possibility that sexual orientation, although an

important variable, may not be the sole determinant of INAH3 [hypothalamus] size.”25

LeVay is an open homosexual, and some comments he made to Newsweek suggest he had an

agenda from the outset of the research. He said he believes that America must be convinced that

homosexuality is biologically determined. “It’s important to educate society,” he said. “I think

this issue does affect religious and legal attitudes.”26

Since LeVay released his study, other researchers have found that life experiences can alter brain

structures, so it is premature to assume inborn origins for behavioral differences. In 1997, for

example, University of California at Berkeley psychologist Marc Breedlove released a study that

showed that sexual activities of rats actually changed structural aspects of the brain at the base of

the spinal chord. Breedlove said:

These findings give us proof for what we theoretically know to be the case—that sexual

experience can alter the structure of the brain, just as genes can alter it. You can’t assume

that because you find a structural difference in the brain, that it was caused by genes. You

don’t know how it got there.27

Breedlove is not an activist out to prove homosexuality is not biological. In fact, he said he

believes that a genetic component exists somewhere and is doing his own research in this area.

The X Chromosome

In 1993, a group of medical researchers at the National Cancer Institute (NCI) led by Dr. Dean

H. Hamer released a study of 40 pairs of brothers that linked homosexuality to the X

chromosome. The research, published in Science, reported that 33 of the pairs of brothers had

DNA markers in the chromosome region known as Xq28.

The study won an enormous amount of media attention, and Hamer’s own activities as a

homosexual activist within NCI were ignored when Hamer offered interviews only when

reporters agreed not to identify him as a homosexual.

But even Hamer tempered his enthusiasm about the research results.

We knew that the genes were only part of the answer,” he said in a speech given in Salt

Lake City. “We assumed the environment also played a role in sexual orientation, as it

does in most, if not all behaviors.28

25 LeVay.

26 D. Gelman, D. Foote, T. Barrett, M. Talbot, “Born or Bred,” Newsweek, 24 February 1992, 46-53.

27 Pat McBroom, “Sexual Experience May Affect Brain Structure,” Berkeleyan campus newspaper (University of California at

Berkeley), 19 November 1997 (http://www.urel.berkeley.edu/berkeleyan/1997/1119/sexexp.html).

28 Dean Hamer, The Science of Desire (New York, New York: Simon & Schuster, 1994), p. 82.

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In a later interview, Hamer said, “Homosexuality is not purely genetic. … [E]nvironmental

factors play a role. There is not a single master gene that makes people gay. …I don’t think we

will ever be able to predict who will be gay.”29

Hamer’s results are often misunderstood. Many believe that the study found an identical

sequence (Xq28) on the X chromosome of all homosexual brothers in the study. In reality, what

it found was matching sequences in each set of brothers who were both homosexual. Dr. Byne

argues that in order to prove anything by this study, Hamer would have had to examine the Xq28

sequence of homosexual men’s heterosexual brothers. Hamer insisted that such an inclusion

would have confounded his study. Byne responds: “In other words, inclusion of heterosexual

brothers might have revealed that something other than genes is responsible for sexual

orientation.”30

In the same edition of Science that carried the Hamer study, Elliot Gershon, chief of the clinical

neurogenetics branch of the National Institute of Mental Health, said, “There’s almost no finding

that would be convincing by itself in this field. We really have to see an independent

replication.”31

The National Cancer Institute sponsored the “gay gene” research. This study alone cost $419,000

of the institute’s taxpayer-backed funds, according to The Washington Times.32

The National Institutes of Health’s Office of Research Integrity investigated Hamer over

allegations by a colleague that he ignored evidence that conflicted with his hypothesis. NIH

never released the results of the inquiry, but Hamer was shortly thereafter transferred to another

section. He had done the “gay gene” research under a grant to work on Kaposi’s Sarcoma, a skin

cancer that inordinately afflicts homosexual men.

One of Hamer’s researchers told the Times that homosexuality is “not the only thing we study,”

but it is “a primary focus of study.” Hamer reportedly stated he has pushed for an Office of Gay

and Lesbian Health inside the National Institutes of Health, and he testified in opposition to

Colorado’s Amendment 2, which sought to keep homosexual activists from winning minority

class status. Then-Sen. Robert C. Smith (R-New Hampshire) accused the doctor of “actively

pursu[ing] … a gay agenda.”33

Another fact that casts doubt on Hamer’s conclusions is that other researchers tried to replicate

his study but failed. In 1999, Drs. George Rice, Neil Risch and George Ebers published their

findings in Science after attempting to replicate Hamer’s Xq28 study. Their conclusion: “We

were not able to confirm evidence for an Xq28-linked locus underlying male homosexuality.”

29 From speech in Salt Lake City in Lili Wright, “Science of Desire Is Topic for ‘Gay Gene’ Finder,” Salt Lake Tribune, 28 April

1995.

30 Byne.

31 “Evidence for Homosexuality Gene,” Science, Vol. 261, 16 July 1993: 291.

32 Joyce Price, “Federal Cancer Lab Hunts for Gay Gene,” The Washington Times, 3 April 1994.

33 Ibid.

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Moreover, they added that when another group of researchers (Sanders, et al.) tried to replicate

Hamer’s study, they too failed to find a genetic connection to homosexuality.34

The Twins Study

In 1991, J. Michael Bailey and Richard C. Pillard published a study that examined identical and

fraternal twin brothers and adopted brothers in an effort to establish a genetic link to

homosexuality. Fifty-two percent of the identical twins were reportedly homosexual, while only

22 percent of fraternal twins fell into the same category. But since identical twins have identical

genetic material, the fact that nearly half of the identical twins were heterosexual effectively

refutes the idea that homosexuality has a genetic basis.35

“This finding alone argues for the enormous importance of nongenetic factors influencing

homosexuality,” writes Dr. Jeffrey Satinover, “because … in order for something to be

genetically determined, as opposed to merely influenced, the genetic heritability would need to

approach 100 percent.”36 Satinover, a psychiatrist, notes that “identical twins reared together

share more significant environmental influences than nonidentical twins reared together,” and

that narcissism, a key component of homosexuality, is more likely among identical twins who

“grow up with mirror images of themselves.”37 (Italics in original.)

In his analysis of the medical evidence purportedly supporting a biological cause of

homosexuality, Dr. Byne noted other twin studies:

Without knowing what developmental experiences contribute to sexual orientation … the

effects of common genes and common environments are difficult to disentangle.

Resolving this issue requires studies of twins raised apart.38

Other physicians have also criticized the study for overvaluing the genetic influence.39

Dr. Byne’s arguments might lead some activists to label him a “homophobe.” He is, in reality,

quite the contrary. Byne readily advocates societal acceptance of homosexuality and “gay

rights,” but nevertheless concludes, “Most of the links in the chain of reasoning from biology to

social policy [regarding homosexuality], do not hold up under scrutiny.”40

Bailey conducted another study in 1999, published in the March 2000 issue of the Journal of

Personality and Social Psychology, which actually showed less possible genetic influence on

homosexuality than the first twins study. He sent a questionnaire to the entire Australian Twin

Registry. Only three pairs of identical male twins were both homosexual out of a total of 27 in

34 Dean H. Hamer, George Rice, Neil Risch, and George Ebers,et al. “Genetics and Male Sexual Orientation” (Technical

Comment), Science 285 (6 August 1999: 803a.

35 J. Michael Bailey, Richard C. Pillard, “A Genetic Study of Male Sexual Orientation,” Archives of General Psychiatry 48

(1991): 1089-96.

36 Satinover, Homosexuality and the Politics of Truth, p. 85.

37 Ibid.

38 Byne.

39 T. Lidz, “A Reply to ‘A Genetic Study of Male Sexual Orientation’” [letter], Archives of General Psychiatry 50 (1993): 240.

40 Ibid.

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which at least one was homosexual. Of the 16 fraternal male twins, none of the pairs was both

homosexual. Bailey found similar results for lesbians.41

Hormones

In 1998, Dennis McFadden and Edward G. Pasanen published a study that evaluated auditory

systems. Specifically, the study considered differences in echo-like waveforms emitted from an

inner ear structure of people with normal hearing. These waves are higher in women than in

men, a factor often attributed to the level of a person’s exposure to androgen (a male hormone)

in his or her early development as a fetus.42

In self-acknowledged lesbians, the waveforms ranged between those of men and those of

heterosexual women. The researchers concluded that this suggests that female homosexuality

could result from larger exposure to the male hormone androgen in the womb (homosexual men

did not show the same variation).43

The media eagerly jumped on this bandwagon. But even the researchers themselves did not

draw definitive conclusions. In the published study, they pointed out that exposure to “intense

sounds, certain drugs, and other manipulations” can lower the level of these auditory waveforms.

“Thus, it may be that something in the lifestyles of homosexual and bisexual females leads them

to be exposed to one or more agents that have reduced the [waveforms], either temporarily or

permanently.”44

Moreover, even if the hearing differences were caused by an increased exposure to androgen in

the womb, scientists would still be far from proving that this exposure is a cause of

homosexuality—especially since the difference was not apparent in the male homosexual

sample.

Finger Length

In March 2000, the media publicized a finger length study that indicated that lesbians had longer

fingers than other women, perhaps because of greater exposure in the womb to androgen.

Typically, both sexes’ index finger is slightly shorter than the ring finger—a difference that is

seen more clearly on the right hand. In females, the ring finger and index finger are almost the

same size, but in men the index finger is more noticeably shorter.

In this study, Berkeley’s Dr. Breedlove, who had in 1997 shown how sexual activity can change

brain structure, found that homosexual women’s finger length had a tendency to follow the male

pattern. But Breedlove cautioned about reading too much into the finding:

41 Stanton L. Jones, “The Incredibly Shrinking Gay Gene,” Christianity Today, 4 October 1999, p. 53.

42 McFadden.

43 Ibid, 2709.

44 Ibid, 2712.

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“There is no gene that forces a person to be straight or gay,” he told CNN. “… I believe there are

many social and psychological, as well as biological, factors that make up sexual preference.”45

Dr. Jeffrey Satinover commented as follows on the study:

A girl who develops before and into puberty with a “masculinized habitus” (the result of

excess maternal intrauterine androgen stimulated by a genetic condition in the fetus)—a

stocky physique, facial hair, powerful muscles, a square jaw and long fingers—may

suffer so much teasing and rejection by family and peers that she comes to think of

herself as “not feminine” and so will seek solace in the arms of women. Indeed, this an

all-too-common pattern in the lives of “ lesbians” and illustrates exactly how a strong

genetic “ association”’ can imply literally zero genetic causation whatsoever. It’s rather

remarkable that the authors failed to remark on the support their study provided not for

any genetic association with lesbianism, but rather for the genetic association to

secondary sexual expression in homo sapiens that Vilain et al were only able to

demonstrate in mus musculus. The attention paid to homosexuality in both cases, while

ignoring straighforward sex, reflects the distinctly Orwellian effect that political

correctness has on science: We now treat the differences between male and female as

socially constructed and those between heterosexuality and homosexuality as innate and

genetic.46

Eye Blinking

In October 2003, a team of English researchers announced that they had found “powerful new

evidence that sexual orientation is ‘hard-wired’ in the human brain before birth.”47

Dr. Qazi Rahman of the University of East London and Dr. Veena Kumari and Dr. Glenn Wilson

of the Institute of Psychiatry said they found sex differences in the startle response – the eye

blink in response to loud noises.48

The authors found that women had a lesser “prepulse inhibition of the human startle response

(PPI),”49 that is, they blinked more readily than men, and that lesbians blinked less readily than

other women. They used small samples, and, more significantly, found no difference between

homosexual men and heterosexual men. Yet they gave the impression that their findings

indicated that homosexuality is a pre-born condition.

45 “Male hormone levels in womb may affect sexual orientation, study says,” CNN.com, health, 29 March 2000,

(http://www.cnn.com/2000/HEALTH/03/29/gay.fingers/index.html).

46 Private communication with the author.

47 “Sexual Orientation ‘hard-wired’ before birth – startling new evidence revealed in the blink of an eye,” press release,

University of East London, England, 2 October 2003.

48 Qazi Rahman, Veena Kumari, and Glenn D. Wilson, “Sexual Orientation-Related Differences in Prepulse Inhibition of the

Human Startle Response,” Behavioral Neuroscience, Vol. 117 (5): 1096-1102.

49Ibid, p. 1096.

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“Because the startle response is known to be involuntary rather than learned, this strongly

indicates that sexual orientation is largely determined before birth,” said a press release from the

University of East London.50

Dr. Rahman said in the release, “These findings may well affect the way we as a society deal

with sexuality and the issues surrounding sexual orientation.”

But the researchers themselves introduce some cautionary notes in the study:

Although prenatal factors may be possible precursors to the neurobehavioral profiles

observed in lesbians and gay men, whether neural differences underlie sexual orientation

per se, or are a consequence of homosexual or heterosexual behavior, is yet to be

determined.51

They also write: “Neuroanatomical and neurophysiological variations between heterosexuals and

homosexuals may be due either to biological factors or to the influence of learning.”52

The team concluded that: “Our results show, for the first time, that PPI relates to sexual

orientation and that homosexual women show a robust cross-sex shift. Homosexual women

showed a masculinized PPI that was no different from that of heterosexual men. … Homosexual

men did not differ from heterosexual men.”53

Dr. Halstead Harrison, an associate professor emeritus in the Atmospheric Science Department

of the University of Washington, reviewed the study, noted the small sizes of the test groups (14

lesbians and 15 heterosexual women, and 15 each of homosexual and heterosexual men) and the

statistical methods, and concluded: “Data presented by Rahman et al. do not confidently support

their finding that homosexual women exhibit a male-type startled-blink reflex.”54

Harrison further stated that “no significant differences were detected.”

As far as the blink reflex being utterly innate or somewhat trainable, he responded to an

interviewer, “Now, that’s an open question.”55 Dr. Harrison also said he would have liked to

have seen the complete data on the series of tests to see whether the subjects’ responses would

change with repetition. This would indicate whether the PPI is entirely innate.

In his conclusion, he said: “This Comment should not be construed as falsifying the hypothesis

that homosexual and heterosexual women display different prepulse startle-inhibition reflexes.

That conjecture may turn out to be so, but the present data do not confidently support it.”

50 Press release, “Sexual orientation ‘hard-wired’ before birth.”

51 Ibid., p. 1097.

52 Ibid,, p. 1099.

53 Ibid,, p. 1098.

54 Halstead Harrison, “A Technical Comment on the paper, ‘Sexual Orientation-Related Differences in Prepulse Inhibition of the

Human Startle Response,’” University of Washington Web site, 15 December 2003,

http://www.atmos.washington.edu/~harrison/reports/rahman.pdf.

55 Telephone interview with Patrick Henry College senior and Culture & Family Institute intern Jeremy Sewall, 8 March 2004.

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Neuroendocrine Hypotheses

In 1999, Dr. Qazi Rahman compiled a brief review of several studies purporting to show a link

between neuroanatomy and sexual orientation.56

He wrote: “The emerging neuroanatomical account suggests that, in some key neural substrates,

homosexual men show a trend toward female-typical neuroanatomy as compared to heterosexual

men.”57

Rahman also said, “Lesbians excel at some tasks which favor heterosexual males.”

As in the eye-blinking study, Rahman struck a cautionary note: “But is neuroendocrine

differentiation a cause or a consequence of behavior? … In addition, the differential

development posited may not be causal but correlational.”

Rahman noted that, “Differential reinforcements from inputs in the psychosocial milieu to these

sex-atypical behaviors makes the ‘pre-homosexual child’ view the same sex as ‘exotic’ (i.e.,

different from one’s self), which later in puberty becomes the object of eroticization.”58

As some developmental psychologists have observed, some children may be less inclined to

exhibit classic gender role differences, and this may set them up for the type of reactions from

peers (or even parents), such as rejection or teasing, that make them vulnerable to developing

same-sex attraction.59

One glaring problem with Rahman’s article is that he uncritically cites many of the studies that

were thoroughly debunked by researchers such as Columbia’s Byne and Parsons. These include

studies by LeVay, Hamer, Allen, Gorski, Bailey and others.

Rahman wraps up his piece this way:

To conclude, it is important to illustrate that neurobiological differences between

homosexuals and heterosexuals are by no means decisive. Nonetheless, the several

independent findings of neuroanatomical differences in sex-atypical directions are not

easily refutable. [Editor’s note: Yes, they are. Byne and Parsons, among others, saw to

that.] Unfortunately, evidence currently available is limited and largely correlational in

nature. Owing to this, it is not possible for alternative developmental processes associated

with sexual orientation to be excluded.60

56 Qazi Rahman, “Comments on the Neuroanatomy of Human Sexual Orientation and Proposed Neuroendocrine Hypotheses,”

Journal of Contemporary Neurology, The MIT Press, Vol. 1999, No. 2A.

57 Ibid,, p. 2.

58 Ibid, p. 3.

59 Numerous references to this phenomenon are reported throughout Joseph Nicolosi, Ph.D., Reparative Therapy of Male

Homosexuality (Northvale, New Jersey: Jason Aronson, Inc., 1991).

60 Rahman, op. cit., p. 3.

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Conclusion

Determining whether something has a biological cause is difficult, and locating a specifically

genetic link is even more so. The handful of studies that purportedly add up to incontestable

“proof” that homosexuals are “born that way” are inconclusive at best and, as Dr. Rahman notes,

“largely correlational in nature.” In some cases, such as the twins studies, the evidence strongly

indicates that early environment is more likely the dominant factor to have produced homosexual

desires.

As Dr. Satinover emphasizes, correlation does not mean something is causative. Basketball

players are tall, so height correlates with playing basketball, he notes. But there is no

“basketball-playing gene.” Efforts to turn some interesting correlations into causal factors have

not been successful and yet have been misused to advance a political agenda.

Perhaps the best way to describe the situation is this, as paraphrased from Dr. Satinover: Some

people may be predisposed because of genetic, prenatal hormonal influences or other physical or

brain differences to have personalities that make them vulnerable to the environmental factors

that can elicit homosexual desires. So is homosexuality biological? Not in the way that popular

media and homosexual activists have presented it.

Extremely shy and artistic young boys, for instance, who are not affirmed in their masculinity by

a caring father, might be at risk for homosexuality. It’s not because of a homosexual “gene,” but

because of an interrupted process of achieving secure gender identity. This can make some boys

who crave male affirmation an easy mark for seduction into homosexuality. A similar pattern can

be seen in girls who don’t fit classic gender profiles, need feminine affirmation, and are targeted

by lesbians who play upon the girls’ emotional needs.

Such children’s vulnerability is all the more reason to protect them from early exposure to

homosexual influences. The Boy Scouts of America, for instance, is right to screen out as troop

leaders those men who desire other males sexually. The Scouts do so not out of bigotry, or a

belief that all homosexual men molest boys. They do so out of genuine concern for the health

and well-being of the boys in their charge, including those who might be sexually vulnerable.

Americans for too long have been pummeled with the idea that people are “born gay.” The

people who most need to hear the truth are those who mistakenly believe they have no chance

themselves for change. It is both more compassionate and truthful to give them hope than to

serve them up politically motivated, unproven creations like the “gay gene.”

Robert Knight is director of the Culture & Family Institute, an affiliate of Concerned Women for

America. This paper is a revised and updated version of “Born & Bred: The Debate Over the

Cause of Homosexuality”(last updated in June 2000) by former Concerned Women for America

staff writer Trudy Chun.

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