UCLA scientists think they've developed the first test that can accurately predict whether a man is gay based on his DNA, and all it takes is a swab of saliva, reports New Scientist. The researchers examined 400,000 epigenetic tags—"chemicals that latch onto DNA and help turn genes on or off," explains BuzzFeed—and zeroed in on five that were notably different in gay and straight twins. A resulting algorithm correctly predicted the men's sexual orientation nearly 70% of the time. Researchers presented the controversial findings at the American Society of Human Genetics annual meeting in Baltimore this week, though they have yet to appear in a peer-reviewed journal. "To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers," says lead author Tuck Ngun in a press release.
A skeptical molecular geneticist said such tests are prone to false positives due to "spurious associations that are down to sheer chance," reports New Scientist. Another added that it needs to be replicated "on larger samples in order to know how good it is, but in theory it's quite interesting." The UCLA researchers used saliva samples from 47 pairs of identical male twins in which at least one of the two was gay. Ngun himself is gay and says he has no intention of pursuing some kind of commercial application for the results. In fact, he's done with the field entirely. "I just left the lab last week," he says. "I don’t believe in the censoring of knowledge, but given the potential for misuse of the information, it just didn’t sit well with me." (Almost one in three young Americans say they are some degree of bisexual.)