Geneticist Dean Hamer says he never chose to be attracted to men. As we talked inside the renovated Washington, D.C., townhouse he shares with his partner and two dogs, the scientist popularly associated with so-called "gay genes" told me he knew he was gay since he was about 5.That's what partly motivated Hamer, 54, to switch from basic molecular genetics to studying sexual orientation in 1992. When he told his colleagues at the National Cancer Institute what he was doing, they were puzzled. "It was pretty far out there," he says. Others thought the answer was too obvious — that of course it was genetic.
But outside the scientific community, Hamer says, it's still widely believed that gay people somehow choose their orientation, and this further fuels discrimination. (President Bush was asked in the presidential debates whether being gay was a choice. He said he didn't know.)
But will studying sexual orientation fight hatred or give it new tools? If scientists identify a "gay gene," will expectant parents use it for selective abortion?
"That scares some straight people away from studying this," says Hamer. "They're afraid of offending someone or causing harm." Most of the leaders in the field are gay, he said, for the same reason female researchers dominate the study of sex differences in the brain.
That limits study of what he considers to be one of the most important aspects of biology and human health. "We have the worst epidemic out there since the plague," he says. "It's spread by sex." Hamer said he was inspired to switch his focus by several studies in the late 1980s, especially one that looked at twins.
If a trait is shared more often by identical twins than by fraternal twins it means there's some genetic component. For men, if one identical twin is gay there's about a 50 percent chance the other will be, too. That falls to about 20 percent if they're fraternal. For women, the story is more complicated, though science shows biology matters there, too.
Hamer realized he might be able to use the tools of molecular genetics to isolate specific genes. He studied 40 pairs of gay brothers and found a particular marker on the X chromosome that was shared more often when both brothers were gay.
When he published his result in 1993 it became known as the "gay gene," but he said this label oversimplified the science. Many straight people have the "gay" version of the marker.
Scientists now know sexual orientation can't be detected from testing any single gene — it's set by a complicated combination of genes and environmental factors.
Only a few studies attempted to replicate Hamer's finding. It remains unresolved. Hamer said other gene findings are followed by hundreds of follow-up studies, but the gay gene is not popular subject matter.
Neuroscientist Charles Wysocki and his colleagues at the Monell Chemical Senses Center in Philadelphia investigated the way male body odor caused spikes in women's hormones.
They found the effect only in straight women, but not lesbians. Intrigued, he followed up with a study suggesting sexual-orientation influences not only how you react to the scents of others but how you yourself smell.
Other startling insights have come from studies of animals. By altering a single gene in fruit flies, researchers in Austria created males who courted and tried to mate with males, females with females. And in Oregon, researchers are finding brain differences between straight and exclusively gay rams.
Scientists say it's next to impossible to get federal funding to research anything related to sex, and especially homosexuality.
And yet our political and cultural debates often hinge on such issues. Should we allow gay marriage? How do we prevent HIV? How do we educate our children so they don't contract and spread this epidemic? How can we deal with anti-gay discrimination?
Science may not have all the answers, but if given the chance, it could at least inform these debates.
from The Seattle Times
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