23andMe Studies the Genetics of Sexual Orientation

(Editor’s note: Here’s a link to Emily’s poster presented at ASHG.)

Earlier this year 23andMe began surveying its customers to study the genetics of sexual orientation. It is now the largest genome-wide association study of sexual orientation ever done.

While our researchers have a strong scientific interest in looking at the understudied role genetics plays in sexual orientation, we started this work, in part, because of the large demand from our customers themselves. It is the most requested topic we’ve ever studied.

But we also began this work because the role genetics plays in sexual orientation is not well studied. The limited work done so far in the field suggests a person’s sexual orientation is partly heritable and our pioneering crowd-sourced research platform offered an opportunity to pursue this work. As 23andMe scientist and research manager Emily Drabant said in a recent interview, we know it is a controversial area.

“I think it’s been hard for groups to get funding to pursue it,” Emily told the Advocate this month. “And maybe also taboo for various research groups to really focus on… 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?’”

We decided to launch the study.

“I think that the 23andMe platform is very conducive to doing research on sensitive topics because people are providing information anonymously from home,” she said. “So we were really excited to launch a study in that area.”

As Emily said our “objective is to be objective.”

Today we are presenting the first return of data we’ve gleaned from our work on sexual orientation at the American Society of Human Genetics annual meeting in San Francisco. As we continue to collect data and expand the number of participants we hope to improve the power of this study, While our researchers did not find – nor did they expect to find – a “gay gene” or even a genetic variant that has a strong association with homosexuality, they did find some interesting routes of inquiry. More than 24,000 customers have participated in the study so far, reflecting the high level of interest in the topic.

A little more than five percent of those people who took the survey identify themselves as solely homosexual, while about 74 percent identified themselves as solely heterosexual. The remainder identified themselves as either mostly, or somewhat homosexual or mostly or somewhat heterosexual, or they identified themselves as bisexual. In the scientific literature, there are small heritability studies of identical and non-identical twins that have suggested sexual orientation is the product of both genetics and environmental factors.

But the strength of the evidence in these studies is limited due to conflicting reports and their small sample sizes. A few of the studies have pointed to possible candidate genes associated with homosexuality found on the X chromosome, specifically on band Xq28, but these studies have been small and only in men. When our researchers looked at band Xq28 they found no direct associations. While we found some gene regions where associations were suggestive, we did not find any that reached a statistical threshold of genome-wide statistical significance.

We believe that as the number of people participating in the study increases – customers can fill out the survey here – the role of the currently suggestive genetic associations may become clearer. Our researchers did replicate previous findings that are unrelated to genetics. These associations and others will help in guiding our research as we continue to conduct our work into the genetics of sexual orientation.

In developing the study we worked with multiple organizations to review our survey questions and help ensure that our research is conducted in an informed and sensitive manner. While these questions cover sensitive topics that some people may view as private, we were encouraged by the numbers of people willing to participate.

The work continues.

  • Altorfer

    Quote.,,While we found some gene regions where associations were suggestive, we did not find any that reached a set threshold of genome-wide statistical significance.”

    Which gene regions near which gene? Please tell me! You are killing me!

    • ScottH

      We will put up a link to the poster presentation that has more detailed information after Emily makes her presentation.

      • altorfer

        where I can find this link?

        • ScottH

          Here is the link to a post that has the links to all the posters presented at ASHG.

  • Kathryn Drabant

    So excited this research is going on. I wish 23 and Me much success in their endeavors and continued willingness of the general public to submit their DNA in order to better understand the human body and mind!


  • Regarding to Prof Sapolsky, and his lessons http://trendingsideways.com/index.php/the-biology-of-human-behavior-robert-sapolskys-key-insights/ , you should focus on epigenetics, not genetics.

    “At the same time, the idea that there is such a thing as “the gay gene” is a myth. As was discussed above, no single gene can be said to cause anything. Furthermore, no single strand of DNA has been found in all gay individuals. There is reason to believe that homosexuality may have more to do with prenatal development and fetal environment than genetics.”

    • Tristanb

      That may be true, Jari. But part of science is finding negatives and establish that certain things do not have an effect. 23andMe has genetic data, not epigenetic data – why would they focus on epigenetics?

      The phenotypic information is interesting if I’m reading it correctly:
      Gay men are less likely to to have played common US sports, and are more likely to cry easily or to have had liposuction. Lesbians are less likely to shave their legs. Surprisingly, gay men are less likely to be atheist or agnostic.

      There seem to be few significant traits amongst lesbians, and I wonder if this is because of fewer exclusively homosexual women and a greater tendency to bisexuality than men.

  • Altorfer

    The NKAIN3 gene is not assocciated with any disease! This gene is also only active in the hypothalamus.
    NKAIN3 knockout mice show ”Temperature-Sensitive Paralytic”! The body temperature a mouse or a human is controlled from the hypothalamus, from the Nucleus preoptici! The Nucleus preoptici is also the center for sexual behavior and sexual preference. The Sexual dimorphic nucleus is reduced in volume by homosexual male rats or homosexual male humans!

    • michelle

      Try not to get so excited…. or is it incensed, Altofer? Those exclamation points are indicative of a phenotypic behavior, you know?

      The most likely cause of male homosexuality is an immune reaction to an environmental trigger while in the womb or in very young life. That most likely trigger is a viral infection. There may some genotypes more susceptible to such a trigger.

  • altorfer

    what it is a poliygenetic caused? The gwas for autisme didn’t show a association, neither! Alzheimer is also a polygenetic disorder! Perhaps some combination o f certain gener caure homosexualitz!

    • Polygenetic = many genes interacting together.

  • You need to add options for asexual. It’s an orientation present in 1% of people, so you should have plenty of asexuals on this site.

  • Miguel

    Im geneticist myself, and got interested on the topic, and by reviewing the pdf file or paper lets say, of the cohort GWAS, for this gay gene…
    One thing is not clear for me. First the methods are very weak, and dont even specify the SNP analyses or the array used… but ok lets move on, then you guys tell on conclusions you found something: “Among men, the peak (non-significant) hit was in chromosome 8q12.3 (chr8:63532921 in NKAIN3, p= 7.1 x 10-8).” but by browsing my genome file, at near those positions like this:

    I clearly verify that, such position (63532921) is not existant on the genome file, nor the RS is specified, this makes me guess, that, the 23andme, Used another genotyping array, not the illumina plus!
    Now my question is, if they used a larger converage array, for that studdy, or even all genome sequencing, why 23andme did not tell about that, or, at least make available that version of the genome array!?

    Iam wrong or something?

    • Altochri

      I think they have imputed SNPs for the suvey. But the fact they haven’t mentioned it is very dubious. Additionally,SNP imputation is not really a way that leads to quality for scientific results. Because a lot of genes succumb recombination!

  • betsgenes

    Twin studies would seem to be very important here. I believe that, so far, the study of identical twins shows that there is some correlation, but not a lot (maybe 50%?). Study of identical twins separated by adoption into different families is probably going to tell us the most. Such twins are harder and harder to find, of course.

    • michelle

      The most comprehensive studies of monozygotic twins shows only a 25% concordance for the trait, meaning that while there must be some kind of genetic component, the environment is the key, probably a bug (more likely to be viral than bacterial) or a toxin to which a certain genotype is susceptible.

  • will

    Neat study. I expect many of the significant associations of homosexuality with behavioral and psychological phenotypes (e.g. tendency to play sports, anxiety and mood disorders) are likely due to the social environment in which gay people grow up, rather than having any genetic basis. When a person grows up in a society that teaches them to be ashamed of oneself, they do not tend to be emotionally healthy.
    One obvious difficulty with any studies of genetic determinants of sexual orientation is that a large percentage of people with same-sex attraction likely suffer from repression, to the degree that they may not even acknowledge their sexual orientation to themselves. It is often said that extremely homophobic people are more likely to suffering from shame and repression of their own homosexuality, and apparently this has been demonstrated, though this research is rather old (http://my.psychologytoday.com/files/u47/Henry_et_al.pdf).
    The difficulty of identifying “true” orientation, and the possible confounding of homophobia and homosexuality, is a major limitation when searching for significant associations between genotype and sexual orientation.
    When I took the sexual orientation survey, I was very glad to see that you included an assessment of attitudes towards homosexuality (table 2), and was hoping that these results could be used to somehow “correct” for self-reporting errors due to repression. Did you explore this at all? In other words, what if you assume that the self-identified “100% straight” males who strongly agreed with the statement “I think male homosexuals are disgusting” are actually homosexual? Would that strengthen an association between homosexuality and any genetic loci? That would be very interesting, indeed!

    • Altochri

      At will

      I’m gay and not happy about that. I believe homosexuality in the most cases is causes through a different hormonal environment in the whomb. In the past I thought homosexuality was a genetic defect which affects 1 % until 2 % of the male population. But after I have seen the presentation of the sexual survey I have changed my opinion. 9% say they were gay. That’s very high. That can not be genetic caused in the most cases. I guess only a small amount of gay men are gay through a genetic disposition. I hope the genome wide association study of sexual orientation will illuminate the genetic behind homosexuality. Perhaps we could find out wich genes are involved for sexual orientation differentation. These genes are also different(not correctly) activated if the hormonal evironment was not usual. That’s called ”phenocopy”.

  • AgentSmith027

    Has anyone tested the genetics of the parents of homosexuals (most notable the mother)? Considering that homosexuality could be determined in utero, I would think that the mothers genetics might play a large role.

    • Irony

      I think that is very likely. It would be interesting to ask not if people are gay, but instead if they have any children who they know are gay. Not perfect of course (parents do not necessarily know that) but it could be interesting.

  • CF

    I clicked on the link but no survey came up among the list. As a homosexual man, I’d really like to contribute to the research but the opportunity is not easy.

    • 23blog

      Although we are still taking information on sexual orientation this particular study has been closed.