Can Your Genes Explain Sexual Orientation?

The future is upon us, and the genetic testing being done now can reveal the past as much as it illuminates the future. The first wave of consumers who embraced it did so to find out about their ancestry. But as testing organizations, particularly 23andMe, the largest and most popular DNA analysis service, grow their databases, consumers are learning many more things about their lives, including which medications they’re likely to have reactions to, whether they have the gene thought to confer immunity to HIV, or — soon — if there’s a genetic root to their sexual orientation.

How it works is simple: Customers buy a saliva kit online at, send it in, and the company extracts their DNA from cheek cells preserved in saliva. In its labs, 23andMe then copies the DNA many times until there’s enough to be genotyped. Then, says lesbian scientist Emily Drabant, the DNA is examined for tens of thousands of genetic variants linked to various conditions and traits, and within weeks users get more than 100 reports on diseases, more than 50 reports on traits, more than 40 reports on carrier status, and more than 20 for drug response.

Drabant, who has a Ph.D. in neuroscience, joined 23andMe three years ago. “We now have one of the largest cohorts of Parkinson’s patients, genotyped patients, in the world — over 9,000 people with Parkinson’s. And we identified two new genes associated with Parkinson’s, which is really exciting.” By having such a large study group, Drabant says, 23andMe was able to explore the genes versus environment question as it relates to the disease. “Within that, we found that, in the part that’s genetic, we know less than 10% of the genes involved. So I think it’s very exciting that there’s still a lot left to discover.”

Indeed, as consumers have used 23andMe to obtain their genetic background, they’ve found plenty of information that is specific to their needs, like cancer risks, HIV resistance and likely progression rate, medication complications, whether they’re prone to substance abuse, who their genetic ancestors are, and whether they are carriers for diseases that put children at risk.

For soon-to-be biological parents, screening for these factors can cost $1,000 per test at a typical medical lab; with 23andMe, a couple hundred bucks tells you the results of dozens of tests.

The most commonly requested test, Drabant says, is for sexual orientation, a particularly controversial area. “I think it’s been hard for groups to get funding to pursue it,” she says. “And maybe also taboo for various research groups to really focus on. So I think that the 23andMe platform is really conducive to doing research on sensitive topics because people are providing information anonymously from home. But that’s the request that came up again and again and again: ‘Can you study sexual orientation? Why aren’t you studying sexual orientation?’ So we were really excited to launch a study in that area.”

The company initiated its sexual orientation project about six months ago, and researchers are hoping that tens of thousands of LGBT folks take the genetic test and fill out the accompanying survey — the information from which allows 23andMe to see patterns among, for example, gay men or transgender women. They don’t know what they’ll find around gender identity yet, says Drabant, but “those are exactly the questions that we’re studying. We asked people about how they identify, including transgender male-to-female, female-to-male, and I think we kind of ask a question more broadly about identity, in terms of masculine and feminine.” Several thousand people have participated in the survey so far, though few identify as transgender.

As soon as the company has a big enough sample, it plans to make those results public, regardless of where they lead.

So far 23andMe has heard from people whose lives have been saved thanks to the information in their genetic tests as well as adopted children who have found their biological families. Researchers have made some discoveries on the lighter side — like if you’re likely to grow back hair or whether cilantro will taste like soap to you — and, Drabant adds, “then we have findings about Parkinson’s, rare blood cancers, and myeloproliferative neoplasms.”

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