The Continuing Search for a Biological Basis of Gayness

The search for a biological basis of homosexuality has come a long way from the "gay gene" searches of the early 1990's. And though research hasn't found simple causes, it has found enough physiological correlations -- hair whorls, finger lengths -- to suggest that gayness is fundamentally innate, though not so simple as to be produced by a mutation or three.

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.

The article's author does a nice job of portraying contemporary research as being in an intermediary stage -- more fine-grained than that of the past, but still unclear, especially on the role of environment.

His discussion of the science is actually clearer than his discussion of the social implications of the science, but these are handled competently, too: if sexuality is innate, some gay people worry that others might try to prevent it (a concern that's always felt overblown to me, and the author also seems to brush it off.) A biological basis for homosexuality could also help to secure gay rights -- though some worry that such a case, by emphasizing biology over conscience, could backfire.

Most interesting, though, is the question of homosexuality's possible social role:

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.

These sorts of theories, which necessarily are tested with fuzzily constructed studies capable of taking a snapshot of the historically ever-changing social roles of gays, won't ever be conclusive. On a social scale, though, it does make sense that both a family and a community would be well-served by having a few strong males, with no breeding responsibilities of their own, around to help gather food, protect the tribe and raise the kids.

Related Wired coverage here.

The Science of Gaydar [New York Magazine]