Aug 29, 2019 - Research

Same-Sex Sexual Behavior Partially Influenced by Genetics

Chromosomes wide

A new genome-wide association study (GWAS) involving more than 490,000 individuals, including 75,000 23andMe customers who consented to research, offers an intriguing glimpse into the complexity of sexual behavior. While the study found thousands of genetic variants with very, very small affects on same-sex sexual behavior, it did not find any “gay gene,” nor did the researchers expect to.


The study, “Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior,” reveals some differences in the genetics of same-sex sexual behavior between men and women, for instance. It also shows that human sexuality is more nuanced than many believe. Rather, like personality and other complex human traits, a mix of genetic and environmental factors influences sexual behavior. 

The researchers — in the United States, the Netherlands, the United Kingdom and Australia, —  did not find any patterns among genetic variants that could be used to meaningfully predict or identify a person’s sexual orientation or behavior. 


“[M]any loci with individually small effects…additively contribute to individual differences in predisposition to same-sex sexual behavior,” they write, describing genetic patterns consistent with many personality, behavioral, and physical traits. 


23andMe is just one of the many institutions involved in this international collaboration, which includes scientists of different disciplines and areas of expertise from some of the world’s top academic and research bodies.


Because it’s a controversial topic, funding has historically been limited and recruitment of participants was difficult — many of the studies that had been done in this area were underpowered and under resourced.


23andMe — with its crowdsourced research platform that allowed anonymous, de-identified participation — was uniquely positioned to engage in this type of study. And, as a company, we are committed to representing the full diversity of the human population, and sexual behavior is just one component of that. 

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