Research: there is no single “gay gene”… sexual orientation can’t be reduced to a genetic on/off switch

According to a recent study to determine if same sex behaviour is down to genetics and if it can be predicted, it has been found that there is no single “gay gene,” instead it is down to a complex mix of genetic and environmental influences, similar to what’s seen for most other human traits. 

The study’s authors say, there are thousands of genetic variants linked to the trait, each with small effects.

The researchers could not find any patterns among genetic variants that could be used to meaningfully predict or identify a person’s sexual behavior, instead they write, describing genetic patterns consistent with many personality, behavioral, and physical traits. In their study, only five genetic variants were “significantly” associated with same-sex behavior, and thousands more appear to also be involved, but taken together these variants had only small effects and are far from being predictive, the authors emphasize. 

In response to the study Fahad Ali, a Research Assistant at the School of Life and Environmental Sciences at the University of Sydney said: “Like all complex human traits, sexual orientation cannot be reduced to a genetic on/off switch,”

“It should be understood that these genetic variations do not determine sexual orientation in any predictive way, and you can have all of these variants without being same-sex attracted (and vice versa).“

While Dr James Morandini, a Postdoctoral Fellow at Social Cognition Individual Differences Laboratory, School of Psychology at the University of Sydney commented: “This is one of the largest studies to-date examining genetic contributions to same-sex sexual behaviour.”

“The study found there is no single ‘gay gene’, but rather there are multiple gene variants that each predict some small amount of the variance in whether someone has engaged in same-sex sexual encounters in the past.”

“Complicating the picture further, the gene variants predicting same-sex sexual behaviour differed between males and females and differed depending on the proportion of same-sex to other-sex partners an individual had.“

And Professor Bob Williamson is the Leader of the Machine Learning Group at NICTA said “The study found that gay men and lesbian women share about half the same gene predictors, but not all.  And most of the samples were from Britain (from the public UK Biobank), but the results agreed with those from 23andMe, a very large US ancestry and health company which had DNA stored from many people who identified as gay.“

“Some individuals who are gay or lesbian will be more influenced by the genetics side, some will be more influenced by environmental factors.“