Freedom in Speech

Written by Lynus Macharia Friday, 29 June 2012 00:00

Some conservatives argue that homosexuality is a personal choice or the result of environmental influences. Some gay rights activists insist that homosexuality is genetic, hoping that proof from that domain will lead to greater acceptance. Still others, backing the same cause, discourage any investigation into the biological origins of sexual orientation, fearful that positive results will lead to attempts to rid the world of potential homosexuals. A handful of scientists, though, are just curious. For them, the discovery of how an individual becomes gay is likely to shed light on how sexuality-related genes build brains, how people of any persuasion are attracted to each other, and perhaps even how homosexuality evolved.

“Who cares about gay men or lesbian women?” asks geneticist Sven Bocklandt of the David Geffen School of Medicine at UCLA. “Sexual selection defines evolution and creation—such a major ­player in determining society—and we have no idea how it works. This is much larger than the gay gene; it’s about all sexual ­reproduction.”  Sven Bocklandt of UCLA's medical school studies the DNA of gay and straight male twins.

Bocklandt was once a mere science journalist. It was while producing documentary for Belgian TV that he first met geneticist Dean Hamer. Hamer had just published a study that claimed not only to have finally proved that male homosexuality was at least partially genetic but also to have pinpointed the stretch of chromosome where one of the genes involved resided. Hamer and his colleagues conducted extensive interviews with 76 pairs of gay brothers and their family members and found that homosexuality seemed to be inherited through the maternal line. This led him to compare the X chromosomes—which can be inherited only from the mother—in those same brothers. There he discovered a shared genetic marker, a patch of DNA called Xq28. Interviews with the subjects also revealed them to be either gay or straight.