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What Makes People Gay?
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?


August 12, 2005
By Neil Swidey

Researcher Alan Sanders signs up Daniel Velez Rivera on Boston Common for a study using gay brothers to search for the genetic basis for homosexuality. (Illustration / Chris Buzelli; Globe Staff Photo / David Kamerman)

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.

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