News

Does Dna Make Some Men Gay?

If gays and lesbians hate one term even more than the crudest epithets hurled at them, it's got to be "lifestyle choice" or "sexual preference." With the implication that gays just casually decide to be attracted to members of the same sex, the phrases have become fighting words in the gay-rights debate. They may also be scientifically wrong. In 1991 a neuroscientist discovered that a tiny structure in the brain is much larger in straight men than in gays, suggesting that biology shapes sexual orientation. Then researchers reported that in pairs of brothers genetically identical twins are more likely to both be gay than are nontwin brothers; this suggested homosexuality springs from heredity. Last week scientists rolled out the strongest evidence yet that the twig is bent by biology. Writing in the journal Science, researchers led by Dean Hamer of the National Cancer Institute conclude that a region on the X chromosome "contributes to homosexual orientation in males."

The NCI team recruited through ads 114 gay men and asked which of their relatives were gay, which straight. More brothers, maternal uncles and sons of maternal aunts were gay than expected, based on the incideuce of' homosexuality in America. But paternal relatives were not more likely to be gay. This pattern of inheritance is typical of traits, such as hemophilia, carried on the X chromosome, which boys inherit only from their mothers. So Hamer analyzed the X chromosomes of 40 pairs of gay, nontwin brothers. Thirty-three of the pairs had five identical lengths of DNA on one tip.

The DNA snippet is long enough to contain hundreds of genes. Hamer's team hasn't found the gene that makes some men gay. That search could take years. But eventually, biologists hope, they will learn how such a gene works, in men as well as women. (The NCI biologists are looking for DNA markers in lesbians, too.) Does it produce a protein that sculpts part of the brain responsible for sexual desire? Make a biochemical involved in temperament or personality? Whatever the gene turns out to be, it is not the only cause of homosexuality. Seven of the 40 pairs of gay brothers did not have the characteristic DNA on their X chromosome. And Hamer has not tested the DNA of straights to see if any carry the snippet, so it's too soon to conclude that it always causes homosexuality. More likely. inheritance and experience together shape sexual orientation.

By linking homosexuality to the genes, says New York psychiatrist Kenneth Paul Rosenberg, Hamer's Study shows that being gay is not "a deviant choice and [the result of] a lack of will. It is at least partly a biological orientation, as important to one's constitution as eve color." Gregory J. King of' the Human Rights Campaign Fund agrees and thinks the finding will have a social impact. "We're very optimistic that this study [will] drive home to the public that sexual orientation is not chosen and help increase support for an end to discrimination" against gays and lesbians.

Or maybe not. Instead, might employers refuse to hire someone with a "gay gene"? Now that clinicians (!an screen for genes in utero, might parents-to-be in the future abort a fetus with the gene? Artists have already thought of it: in "The Twilight of the Golds," now playing in Washington, D.C., a woman learns her unborn son will be gay and debates whether to abort him. Hamer was so troubled by such possibilities that he ended his technical, abstruse paper with an unusual plea: "We believe that it would be fundamentally unethical to use such [genetic] information to try to assess or alter a person's Current or future sexual orientation." Scientists can hope all they want that society won't misuse their findings. But hope without ethical guidelines or laws has never been enough.