[Paleopsych] Boston Globe: What Makes People Gay?

[Premise Checker]

What Makes People Gay?
http://www.boston.com/news/globe/magazine/articles/2005/08/14/what_makes_people_gay?mode=PF

The debate has always been that it was either all in the child's upbringing
or all in the genes. But what if it's something else?

    By Neil Swidey  |  August 14, 2005

    With crystal-blue eyes, wavy hair, and freshly scrubbed faces, the
    boys look as though they stepped out of a Pottery Barn Kids catalog.
    They are 7-year-old twins. I'll call them Thomas and Patrick; their
    parents agreed to let me meet the boys as long as I didn't use their
    real names.

    Spend five seconds with them, and there can be no doubt that they are
    identical twins - so identical even they can't tell each other apart
    in photographs. Spend five minutes with them, and their profound
    differences begin to emerge.

    Patrick is social, thoughtful, attentive. He repeatedly addresses me
    by name. Thomas is physical, spontaneous, a bit distracted. Just
    minutes after meeting me outside a coffee shop, he punches me in the
    upper arm, yells, "Gray punch buggy!" and then points to a Volkswagen
    Beetle cruising past us. It's a hard punch. They horse around like
    typical brothers, but Patrick's punches are less forceful and his
    voice is higher. Thomas charges at his brother, arms flexed in front
    of him like a mini-bodybuilder. The differences are subtle - they're
    7-year-old boys, after all - but they are there.

    When the twins were 2, Patrick found his mother's shoes. He liked
    wearing them. Thomas tried on his father's once but didn't see the
    point.

    When they were 3, Thomas blurted out that toy guns were his favorite
    things. Patrick piped up that his were the Barbie dolls he discovered
    at day care.

    When the twins were 5, Thomas announced he was going to be a monster
    for Halloween. Patrick said he was going to be a princess. Thomas said
    he couldn't do that, because other kids would laugh at him. Patrick
    seemed puzzled. "Then I'll be Batman," he said.

    Their mother - intelligent, warm, and open-minded - found herself
    conflicted. She wanted Patrick - whose playmates have always been
    girls, never boys - to be himself, but she worried his feminine
    behavior would expose him to ridicule and pain. She decided to allow
    him free expression at home while setting some limits in public.

    That worked until last year, when a school official called to say
    Patrick was making his classmates uncomfortable. He kept insisting
    that he was a girl.

    Patrick exhibits behavior called childhood gender nonconformity, or
    CGN. This doesn't describe a boy who has a doll somewhere in his toy
    collection or tried on his sister's Snow White outfit once, but rather
    one who consistently exhibits a host of strongly feminine traits and
    interests while avoiding boy-typical behavior like rough-and-tumble
    play. There's been considerable research into this phenomenon,
    particularly in males, including a study that followed boys from an
    early age into early adulthood. The data suggest there is a very good
    chance Patrick will grow up to be homosexual. Not all homosexual men
    show this extremely feminine behavior as young boys. But the research
    indicates that, of the boys who do exhibit CGN, about 75 percent of
    them - perhaps more - turn out to be gay or bisexual.

    What makes the case of Patrick and Thomas so fascinating is that it
    calls into question both of the dominant theories in the long-running
    debate over what makes people gay: nature or nurture, genes or learned
    behavior. As identical twins, Patrick and Thomas began as genetic
    clones. From the moment they came out of their mother's womb, their
    environment was about as close to identical as possible - being fed,
    changed, and plopped into their car seats the same way, having similar
    relationships with the same nurturing father and mother. Yet before
    either boy could talk, one showed highly feminine traits while the
    other appeared to be "all boy," as the moms at the playgrounds say
    with apologetic shrugs.

    "That my sons were different the second they were born, there is no
    question about it," says the twins' mother.

    So what happened between their identical genetic starting point and
    their births? They spent nine months in utero. In the hunt for what
    causes people to be gay or straight, that's now the most interesting
    and potentially enlightening frontier.

    WHAT DOES IT MATTER WHERE HOMOSEXUALITY COMES FROM? Proving people are
    born gay would give them wider social acceptance and better protection
    against discrimination, many gay rights advocates argue. In the last
    decade, as this "biological" argument has gained momentum, polls find
    Americans - especially young adults - increasingly tolerant of gays
    and lesbians. And that's exactly what has groups opposed to
    homosexuality so concerned. The Family Research Council, a
    conservative Christian think tank in Washington, D.C., argues in its
    book Getting It Straight that finding people are born gay "would
    advance the idea that sexual orientation is an innate characteristic,
    like race; that homosexuals, like African-Americans, should be legally
    protected against 'discrimination;' and that disapproval of
    homosexuality should be as socially stigmatized as racism. However, it
    is not true."

    Some advocates of gay marriage argue that proving sexual orientation
    is inborn would make it easier to frame the debate as simply a matter
    of civil rights. That could be true, but then again, freedom of
    religion enjoyed federal protection long before inborn traits like
    race and sex.

    For much of the 20th century, the dominant thinking connected
    homosexuality to upbringing. Freud, for instance, speculated that
    overprotective mothers and distant fathers helped make boys gay. It
    took the American Psychiatric Association until 1973 to remove
    "homosexuality" from its manual of mental disorders.

    Then, in 1991, a neuroscientist in San Diego named Simon LeVay told
    the world he had found a key difference between the brains of
    homosexual and heterosexual men he studied. LeVay showed that a tiny
    clump of neurons of the anterior hypothalamus - which is believed to
    control sexual behavior - was, on average, more than twice the size in
    heterosexual men as in homosexual men. LeVay's findings did not speak
    directly to the nature-vs.-nurture debate - the clumps could,
    theoretically, have changed size because of homosexual behavior. But
    that seemed unlikely, and the study ended up jump-starting the effort
    to prove a biological basis for homosexuality.

    Later that same year, Boston University psychiatrist Richard Pillard
    and Northwestern University psychologist J. Michael Bailey announced
    the results of their study of male twins. They found that, in
    identical twins, if one twin was gay, the other had about a 50 percent
    chance of also being gay. For fraternal twins, the rate was about 20
    percent. Because identical twins share their entire genetic makeup
    while fraternal twins share about half, genes were believed to explain
    the difference. Most reputable studies find the rate of homosexuality
    in the general population to be 2 to 4 percent, rather than the
    popular "1 in 10" estimate.

    In 1993 came the biggest news: Dean Hamer's discovery of the "gay
    gene." In fact, Hamer, a Harvard-trained researcher at the National
    Cancer Institute, hadn't quite put it that boldly or imprecisely. He
    found that gay brothers shared a specific region of the X chromosome,
    called Xq28, at a higher rate than gay men shared with their straight
    brothers. Hamer and others suggested this finding would eventually
    transform our understanding of sexual orientation.

    That hasn't happened yet. But the clear focus of sexual-orientation
    research has shifted to biological causes, and there hasn't been much
    science produced to support the old theories tying homosexuality to
    upbringing. Freud may have been seeing the effect rather than the
    cause, since a father faced with a very feminine son might well become
    more distant or hostile, leading the boy's mother to become more
    protective. In recent years, researchers who suspect that
    homosexuality is inborn - whether because of genetics or events
    happening in the womb - have looked everywhere for clues: Prenatal
    hormones. Birth order. Finger length. Fingerprints. Stress. Sweat. Eye
    blinks. Spatial relations. Hearing. Handedness. Even "gay" sheep.

    LeVay, who is gay, says that when he published his study 14 years ago,
    some gays and lesbians criticized him for doing research that might
    lead to homosexuality once again being lumped in with diseases and
    disorders. "If anything, the reverse has happened," says LeVay, who is
    now 61 and no longer active in the lab. He says the hunt for a
    biological basis for homosexuality, which involves many researchers
    who are themselves gay or lesbian, "has contributed to the status of
    gay people in society."

    These studies have been small and underfunded, and the results have
    often been modest. Still, because there's been so much of this
    disparate research, "all sort of pointing in the same direction, makes
    it pretty clear there are biological processes significantly
    influencing sexual orientation," says LeVay. "But it's also kind of
    frustrating that it's still a bunch of hints, that nothing is really
    as crystal clear as you would like."

    Just in the last few months, though, the hints have grown stronger.

    In May, Swedish researchers reported finding important differences in
    how the brains of straight men and gay men responded to two compounds
    suspected of being pheromones - those scent-related chemicals that are
    key to sexual arousal in animals. The first compound came from women's
    urine, the second from male sweat. Brain scans showed that when
    straight men smelled the female urine compound, their hypothalamus lit
    up. That didn't happen with gay men. Instead, their hypothalamus lit
    up when they smelled the male-sweat compound, which was the same way
    straight women had responded. This research once again connecting the
    hypothalamus to sexual orientation comes on the heels of work with
    sheep. About 8 percent of domestic rams are exclusively interested in
    sex with other rams. Researchers found that a clump of neurons similar
    to the one LeVay identified in human brains was also smaller in gay
    rams than straight ones. (Again, it's conceivable that these
    differences could be showing effect rather than cause.)

    In June, scientists in Vienna announced that they had isolated a
    master genetic switch for sexual orientation in the fruit fly. Once
    they flicked the switch, the genetically altered female flies rebuffed
    overtures from males and instead attempted to mate with other females,
    adopting the elaborate courting dance and mating songs that males use.

    And now, a large-scale, five-year genetic study of gay brothers is
    underway in North America. The study received $2.5 million from the
    National Institutes of Health, which is unusual. Government funders
    tend to steer clear of sexual orientation research, aware that even
    small grants are apt to be met with outrage from conservative
    congressmen looking to make the most of their C-Span face time.
    Relying on a robust sample of 1,000 gay-brother pairs and the latest
    advancements in genetic screening, this study promises to bring some
    clarity to the murky area of what role genes may play in
    homosexuality.

    This accumulating biological evidence, combined with the prospect of
    more on the horizon, is having an effect. Last month, the Rev. Rob
    Schenck, a prominent Washington, D.C., evangelical leader, told a
    large gathering of young evangelicals that he believes homosexuality
    is not a choice but rather a predisposition, something "deeply rooted"
    in people. Schenck told me that his conversion came about after he'd
    spoken extensively with genetic researchers and psychologists. He
    argues that evangelicals should continue to oppose homosexual
    behavior, but that "many evangelicals are living in a sort of state of
    denial about the advance of this conversation." His message: "If it's
    inevitable that this scientific evidence is coming, we have to be
    prepared with a loving response. If we don't have one, we won't have
    any credibility."

    AS THE 21-YEAR-OLD COLLEGE JUNIOR IN A HOSPITAL JOHNNY slides into the
    MRI, she is handed controls with buttons for "strongly like" and
    "strongly dislike." Hundreds of pornographic images - in male-male and
    female-female pairings - flash before her eyes. Eroticism eventually
    gives way to monotony, and it's hard to avoid looking for details to
    distinguish one image from the rest of the panting pack. So it goes
    from "Look at the size of those breasts!" to "That can't be
    comfortable, given the length of her fingernails!" to "Why is that guy
    wearing nothing but work boots on the beach?"

    Regardless of which buttons the student presses, the MRI scans show
    her arousal level to each image, at its starting point in the brain.

    Researchers at Northwestern University, outside Chicago, are doing
    this work as a follow-up to their studies of arousal using genital
    measurement tools. They found that while straight men were aroused by
    film clips of two women having sex, and gay men were aroused by clips
    of two men having sex, most of the men who identified themselves as
    bisexual showed gay arousal patterns. More surprising was just how
    different the story with women turned out to be. Most women, whether
    they identified as straight, lesbian, or bisexual, were significantly
    aroused by straight, gay, and lesbian sex. "I'm not suggesting that
    most women are bisexual," says Michael Bailey, the psychology
    professor whose lab conducted the studies. "I'm suggesting that
    whatever a woman's sexual arousal pattern is, it has little to do with
    her sexual orientation." That's fundamentally different from men. "In
    men, arousal is orientation. It's as simple as that. That's how gay
    men learn they are gay."

    These studies mark a return to basics for the 47-year-old Bailey. He
    says researchers need a far deeper understanding of what sexual
    orientation is before they can determine where it comes from.

    Female sexual orientation is particularly foggy, he says, because
    there's been so little research done. As for male sexual orientation,
    he argues that there's now enough evidence to suggest it is "entirely
    in-born," though not nearly enough to establish how that happens.

    Bailey's 1991 twin study is still cited by other researchers as one of
    the pillars in the genetic argument for homosexuality. But his
    follow-up study using a comprehensive registry of twins in Australia
    found a much lower rate of similarity in sexual orientation between
    identical twins, about 20 percent, down from 50 percent. Bailey still
    believes that genes make important contributions to sexual
    orientation. But, he says, "that's not where I'd bet the real
    breakthroughs will come."

    His hunch is that further study of childhood gender nonconformity will
    pay big. Because it's unclear what percentage of homosexuals and
    lesbians showed CGN as children, Bailey and his colleagues are now
    running a study that uses adult participants' home movies from
    childhood to look for signs of gender-bending behavior.

    Cornell psychologist Daryl Bem has proposed an intriguing theory for
    how CGN might lead to homosexuality. According to this pathway, which
    he calls "the exotic becomes erotic," children are born with traits
    for temperament, such as aggression and activity level, that
    predispose them to male-typical or female-typical activities. They
    seek out playmates with the same interests. So a boy whose traits lead
    him to hopscotch and away from rough play will feel different from,
    and ostracized by, other boys. This leads to physiological arousal of
    fear and anger in their presence, arousal that eventually is
    transformed from exotic to erotic.

    Critics of homosexuality have used Bem's theory, which stresses
    environment over biology, to argue that sexual orientation is not
    inborn and not fixed. But Bem says this pathway is triggered by
    biological traits, and he doesn't really see how the outcome of
    homosexuality can be changed.

    Bailey says whether or not Bem's theory holds up, the environment most
    worth focusing in on is the one a child experiences when he's in his
    mother's womb.

    LET'S GET BACK TO THOMAS AND PATRICK. BECAUSE IT'S UNCLEAR why twin
    brothers with identical genetic starting points and similar post-birth
    environments would take such divergent paths, it's helpful to return
    to the beginning.

    Males and females have a fundamental genetic difference - females have
    two X chromosomes, and males have an X and a Y. Still, right after
    conception, it's hard to tell male and female zygotes apart, except
    for that tucked-away chromosomal difference. Normally, the changes
    take shape at a key point of fetal development, when the male brain is
    masculinized by sex hormones. The female brain is the default. The
    brain will stay on the female path as long as it is protected from
    exposure to hormones. The hormonal theory of homosexuality holds that,
    just as exposure to circulating sex hormones determines whether a
    fetus will be male or female, such exposure must also influence sexual
    orientation.

    The cases of children born with disorders of "sexual differentiation"
    offer insight. William Reiner, a psychiatrist and urologist with the
    University of Oklahoma, has evaluated more than a hundred of these
    cases. For decades, the standard medical response to boys born with
    severely inadequate penises (or none at all) was to castrate the boy
    and have his parents raise him as a girl. But Reiner has found that
    nurture - even when it involves surgery soon after birth - cannot
    trump nature. Of the boys with inadequate penises who were raised as
    girls, he says, "I haven't found one who is sexually attracted to
    males." The majority of them have transitioned back to being males and
    report being attracted to females.

    During fetal development, sexual identity is set before the sexual
    organs are formed, Reiner says. Perhaps it's the same for sexual
    orientation. In his research, of all the babies with X and Y
    chromosomes who were raised as girls, the only ones he has found who
    report having female identities and being attracted to males are those
    who did not have "receptors" to let the male sex hormones do their
    masculinizing in the womb.

    What does this all mean? "Exposure to male hormones in utero
    dramatically raises the chances of being sexually attracted to
    females," Reiner says. "We can infer that the absence of male hormone
    exposure may have something to do with attraction to males."

    Michael Bailey says Reiner's findings represent a major breakthrough,
    showing that "whatever causes sexual orientation is strongly
    influenced by prenatal biology." Bailey and Reiner say the answer is
    probably not as simple as just exposure to sex hormones. After all,
    the exposure levels in some of the people Reiner studies are abnormal
    enough to produce huge differences in sexual organs. Yet, sexual
    organs in straight and gay people are, on average, the same. More
    likely, hormones are interacting with other factors.

    Canadian researchers have consistently documented a "big-brother
    effect," finding that the chances of a boy being gay increase with
    each additional older brother he has. (Birth order does not appear to
    play a role with lesbians.) So, a male with three older brothers is
    three times more likely to be gay than one with no older brothers,
    though there's still a better than 90 percent chance he will be
    straight. They argue that this results from a complex interaction
    involving hormones, antigens, and the mother's immune system.

    By now, there is substantial evidence showing correlation - though not
    causation - between sexual orientation and traits that are set when a
    baby is in the womb. Take finger length. In general, men have shorter
    index fingers in relation to their ring fingers; in women, the lengths
    are generally about the same. Researchers have found that lesbians
    generally have ratios closer to males. Other studies have shown
    masculinized results for lesbians in inner-ear functions and eye-blink
    reactions to sudden loud noises, and feminized patterns for gay men on
    certain cognitive tasks like spatial perception and remembering the
    placement of objects.

    New York University researcher Lynn S. Hall, who has studied traits
    determined in the womb, speculates that Patrick was somehow prenatally
    stressed, probably during the first trimester, when the brain is
    really developing, particularly the structures like the hypothalamus
    that influence sexual behavior. This stress might have been based on
    his position in the womb or the blood flow to him or any of a number
    of other factors not in his mother's control. Yet more evidence that
    identical twins have womb experiences far from identical can be found
    in their often differing birth weights. Patrick was born a pound
    lighter than Thomas.

    Taken together, the research suggests that early on in the womb, as
    the fetus's brain develops in either the male or female direction,
    something fundamental to sexual orientation is happening. Nobody's
    sure what's causing it. But here's where genes may be involved,
    perhaps by regulating hormone exposure or by dictating the size of
    that key clump of neurons in the hypothalamus. Before researchers can
    sort that out, they'll need to return to the question of whether, in
    fact, there is a "gay gene."

    THE CROWD ON BOSTON COMMON IS THICK ON THIS SCORCHER of a Saturday
    afternoon in June, as the throngs make their way around the 35th
    annual Boston Pride festival, past booths peddling everything from
    "Gayopoly" board games to Braveheartian garments called Utilikilts.
    Sitting quietly in his booth is Alan Sanders, a soft-spoken
    41-year-old with a sandy beard and thinning hair. He's placed a mound
    of rainbow-colored Starbursts on the table in front of him and hung a
    banner that reads: "WANTED: Gay Men with Gay Brothers for Molecular
    Genetic Study of Sexual Orientation."

    Sanders is a psychiatrist with the Evanston Northwestern Healthcare
    Research Institute who is leading the NIH-funded search for the
    genetic basis of male homosexuality ([2]www.gaybros.com). He is
    spending the summer crisscrossing the country, going to gay pride
    festivals, hoping to recruit 1,000 pairs of gay brothers to
    participate. (His wife, who just delivered their third son, wasn't
    crazy about the timing.) When people in Boston ask him how much genes
    may contribute to homosexuality, he says the best estimate is about 40
    percent.

    Homosexuality runs in families - studies show that 8 to 12 percent of
    brothers of gay men are also gay, compared with the 2 to 4 percent of
    the general population.

    Sanders spends much of the afternoon handing out Starbursts to people
    who clearly don't qualify for a gay brothers study - preteen girls,
    adult lesbians wearing T-shirts that read "I Like Girls Who Like
    Girls," and elderly women in straw hats who speak only Chinese. But
    many of the gay men who stop by are interested in more than free
    candy. Among the people signing up is James Daly, a 31-year-old from
    Salem. "I think it's important for the public - especially the
    religious right - to know it's not a choice for some people," Daly
    says. "I feel I was born this way."

    (In fairness, there aren't many leaders of groups representing social
    and religious conservatives who still argue that homosexual
    orientation - as opposed to behavior - is a matter of choice. Even as
    he insists that no one is born gay, Peter Sprigg, the point person on
    homosexuality for the Family Research Council, says, "I don't think
    that people choose their sexual attraction.")

    In the decade since Dean Hamer made headlines, the gay gene theory has
    taken some hits. A Canadian team was unable to replicate his findings.
    Earlier this year, a team from Hamer's own lab reported only mixed
    results after having done the first scan of the entire human genome in
    the search for genes influencing sexual orientation.

    But all of the gene studies so far have been based on small samples
    and lacked the funding to do things right. Sanders's study should be
    big enough to provide some real answers on linkage as well as shed
    light on gender nonconformity and the big-brother effect.

    There is, however, a towering question that Sanders's study will
    probably not be able to answer. That has to do with evolution. If a
    prime motivation of all species is to pass genes on to future
    generations, and gay men are estimated to produce 80 percent fewer
    offspring than straight men, why would a gay gene not have been wiped
    out by the forces of natural selection? This evolutionary disadvantage
    is what led former Amherst College biologist Paul Ewald to argue that
    homosexuality might be caused by a virus - a pathogen most likely
    working in utero. That argument caused a stir when he and a colleague
    proposed it six years ago, but with no research done to test it, it
    remains just another theory. Other scientists have offered fascinating
    but unpersuasive explanations, most of them focusing on some kind of
    compensatory benefit, in the same way that the gene responsible for
    sickle cell anemia also protects against malaria. A study last year by
    researchers in Italy showed that female relatives of gay men tended to
    be more fertile, though, as critics point out, not nearly fertile
    enough to make up for the gay man's lack of offspring.

    But there will be plenty of time for sorting out the evolutionary
    paradox once - and if - researchers are able to identify actual genes
    involved in sexual orientation. Getting to that point will likely
    require integrating multiple lines of promising research. That is
    exactly what's happening in Eric Vilain's lab at the University of
    California, Los Angeles. Vilain, an associate professor of human
    genetics, and his colleague, Sven Bocklandt, are using gay sheep,
    transgenic mice, identical twin humans, and novel approaches to human
    genetics to try to unlock the mystery of sexual orientation.

    Instead of looking for a gay gene, they stress that they are looking
    for several genes that cause either attraction to men or attraction to
    women. Those same genes would work one way in heterosexual women and
    another way in homosexual men. The UCLA lab is examining how these
    genes might be turned "up" or "down." It's not a question of what
    genes you have, but rather which ones you use, says Bocklandt. "I have
    the genes in my body to make a vagina and carry a baby, but I don't
    use them, because I am a man." In studying the genes of gay sheep, for
    example, he's found some that are turned "way up" compared with the
    straight rams.

    The lab is also testing an intriguing theory involving imprinted
    genes. Normally, we have two copies of every gene, one from each
    parent, and both copies work. They're identical, so it doesn't matter
    which copy comes from which parent. But with imprinted genes, that
    does matter. Although both copies are physically there, one copy -
    either from the mom or the dad - is blocked from working. Think of an
    airplane with an engine on each wing, except one of the engines is
    shut down. A recent Duke University study suggests humans have
    hundreds of imprinted genes, including one on the X chromosome that
    previous research has tied to sexual orientation.

    With imprinted genes, there is no backup engine. So if there's
    something atypical in the copy from mom, the copy from dad cannot be
    turned on. The UCLA lab is now collecting DNA from identical twins in
    which one twin is straight and the other is gay. Because the twins
    begin as genetic clones, if a gene is imprinted in one twin, it will
    be in the other twin as well. Normally, as the fetuses are developing,
    each time a cell divides, the DNA separates and makes a copy of
    itself, replicating all kinds of genetic information. It's a
    complicated but incredibly accurate process. But the coding to keep
    the backup engine shut down on an imprinted gene is less accurate.

    So how might imprinted genes help explain why one identical twin would
    be straight and the other gay? Say there's an imprinted gene for
    attraction to females, and there's something atypical in the copy the
    twin brothers get from mom. As all that replicating is going on, the
    imprinting (to keep the copy from dad shut down) proceeds as expected
    in one twin, and he ends up gay. But somehow with his brother, the
    coding for the imprinting is lost, and rather than remain shut down,
    the fuel flows to fire up the backup engine from dad. And that twin
    turns out to be straight.

    IN THE COURSE OF REPORTING THIS STORY, I EXPERIENCED A good deal of
    whiplash. Just when I would become swayed by the evidence supporting
    one discreet theory, I would stumble onto new evidence casting some
    doubt on it. Ultimately, I accepted this as unavoidable terrain in the
    hunt for the basis of sexual orientation. This is, after all, a
    research field built on underfunded, idiosyncratic studies that are
    met with full-barreled responses from opposing and well-funded
    advocacy groups determined to make the results from the lab hew to the
    scripts they've honed for the talk-show circuit.

    You can't really blame the advocacy groups. The stakes are high. In
    the end, homosexuality remains such a divisive issue that only
    thoroughly tested research will get society to accept what science has
    to say about its origin. Critics of funding for sexual orientation
    research say that it isn't curing cancer, and they're right. But we
    devote a lot more dollars to studying other issues that aren't curing
    cancer and have less resonance in society.

    Still, no matter how imperfect these studies are, when you put them
    all together and examine them closely, the message is clear: While
    post-birth development may well play a supporting role, the roots of
    homosexuality, at least in men, appear to be in place by the time a
    child is born. After spending years sifting through all the available
    data, British researchers Glenn Wilson and Qazi Rahman come to an even
    bolder conclusion in their forthcoming book Born Gay: The
    Psychobiology of Sex Orientation, in which they write: "Sexual
    orientation is something we are born with and not `acquired' from our
    social environment."

    Meanwhile, the mother of twins Patrick and Thomas has done her own
    sifting and come to her own conclusions. She says her son's feminine
    behavior suggests he will grow up to be gay, and she has no problem
    with that. She just worries about what happens to him between now and
    then.

    After that fateful call from Patrick's school, she says, "I knew I had
    to talk to my son, and I had no clue what to say." Ultimately, she
    told him that although he could play however he wanted at home, he
    couldn't tell his classmates he was a girl, because they'd think he
    was lying. And she told him that some older boys might be mean to him
    and even hit him if he continued to claim he was a girl.

    Then she asked him, "Do you think that you can convince yourself that
    you are a boy?"

    "Yes, Mom," he said. "It's going to be like when I was trying to learn
    to read, and then one day I opened the book and I could read."

    His mother's heart sank. She could tell that he wanted more than
    anything to please her. "Basically, he was saying there must be a
    miracle - that one day I wake up and I'm a boy. That's the only way he
    could imagine it could happen."

    In the year since that conversation, Patrick's behavior has become
    somewhat less feminine. His mother hopes it's just because his
    interests are evolving and not because he's suppressing them.

    "I can now imagine him being completely straight, which I couldn't a
    year ago," she says. "I can imagine him being gay, which seems to be
    statistically most likely."

    She says she's fine with either outcome, just as long as he's happy
    and free from harm. She takes heart in how much more accepting today's
    society is. "By the time my boys are 20, the world will have changed
    even more."

    By then, there might even be enough consensus for researchers to
    forget about finger lengths and fruit flies and gay sheep, and move on
    to a new mystery.

    Neil Swidey is a member of the Globe Magazine staff. He can be reached
    at [3]swidey at globe.com.