Searching for That Perfect Pair of Genes

Article excerpt

The most important development in science in the next 30 years will be the sequencing of the human genome. By the 60th anniversary of The Advocate, we will have a complete picture of every single one of the 100,000 or so genes that determine all our inherited characteristics, including how we look, the way we think, even whom we sleep with.

My own laboratory and others have already discovered genetic information involved in determining whether we are born male or female, whether we are gay or straight, and how many sexual partners we will have. Soon we will know much more about the genes that are responsible for making penises and vaginas and breasts, that specify the neuronal wiring that connects the sexual organs to pleasure and pain centers in the brain, that synthesize and degrade the brain chemicals involved in sexual arousal and libido, and that play a role in sexual attraction to men, women, or both.

What will be the implications of this research for gay, lesbian, and bisexual people? Probably less significant than you think.

The reason is that sexuality is too complex to ever be completely explained by genes. Although DNA may influence brain chemistry and thus tilt us to feel and behave in particular ways, it does not govern sexual identity. Predisposition is not predetermination. The social and cultural environment will always play a major role, as will chance and serendipity, choice and free will.

The fantasy that people have is a test that would determine the sexual orientation of a fetus. The doctor sits down with prospective parents and announces, "You have a perfectly healthy baby boy due in three months. He does not have any genetic abnormalities. He will grow up to be gay."

That's not going to happen. The Twilight of the Golds was science fiction, not science. In real life a doctor who tried to base a prognosis on the X-linked "gay gene" that my laboratory discovered in 1993 might be able to say something like, "Your baby has an 8.3% chance of being gay." But even if he or she looked at every one of the 100,000 genes in the fetus, the most accurate prediction the doctor could possibly make would be 50-50. If the fetus were a girl, the prediction would be even less certain, since research shows that inheritance plays a weaker role in female sexual orientation.

Will there ever be a home test for the gay gene in adults? Maybe, but it wouldn't tell you much. A home test works for something like pregnancy because you can't be a little bit pregnant. …