There’s Now A Genetic Test For Homosexuality (Sort Of)

With less than one week to go before National Coming Out may have just "outed" you

(Illustration: Diana Quach/Vocativ)
Oct 08, 2015 at 4:16 PM ET

There may not be one, all-encompassing Gay Gene but scientists have long suspected that our sexuality has its origins in our DNA. Now, just in time for National Coming Out Day, researchers have developed an algorithm that, they say, can predict male sexual orientation with 70 percent accuracy by scanning nine regions of the human genome. They presented their findings at the American Society of Human Genetics in Baltimore.

“To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers,” said coauthor Tuck C. Ngun, of the University of California, Los Angeles in a prepared statement.

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It all boils down to the relatively young scientific field of epigenetics, the study of how external factors can activate genes or change how cells read DNA. When you’re dealing with epigenetics, even seemingly minor chemical modifications can have long-lasting effects. In fact, a 2012 paper suggested tiny carbohydrates called methyl groups may make epigenetic changes to sperm and egg cells, influencing the sexual orientation of the baby.

The latest research builds on that theory, by examining the methyl groups present in 140,000 regions within the genetic code. The scientists specifically studied a group of “discordant” (one gay, one straight) male identical twins—most of whom share all the same genes. They found that sexual orientation among the twins was strongly linked to certain methylation patterns along nine regions in the DNA. When they then interviewed the twins, the researchers found that the patterns functioned as a sort of epigenetic gaydar, which identified male homosexuality with nearly 70 percent accuracy.

Theories as to why these methyl groups latch onto specific DNA regions abound. “Methylation may be determined by subtle differences in the environment each fetus experiences during gestation, such as their exact locations within the womb and how much of the maternal blood supply each receives,” writes Michael Balter, reporter at Science Magazine.

More So How Exactly Is Kuwait Going to “Medically Test” People to Detect If They Are Gay?

Meanwhile, there is no indication that this test could be used to detect homosexuality outside of the laboratory. It’s not as if you tick a box on a blood test and have your children tested, for example. And that (of course) is a good thing, because you can’t guarantee the motives of people who would do such a thing. Places like Kuwait, for instance, have already expressed interest in a medical test to help them identify, and then discriminate against, gay people. Fortunately, the researchers have no intention of using their results to detect or “cure” homosexuality—and it seems unlikely that scientists could do such a thing, anyway. “We will not have the potential to manipulate sexual orientation anytime soon,” psychologist J. Michael Bailey of Northwestern University in Illinois told Balter.

But even if the results could throw us onto shaky ethical ground, Bailey stresses that sexual orientation research must remain unfettered by its social or political implications. “We should not restrict research on the origins of sexual orientation on the basis of hypothetical or real implications,” he said.