There is no single “gay gene”, according to an article in Science which analyses survey responses about same-sex sexual behaviour and correlates them with genetic data.
The researchers could not find any way to meaningfully predict or identify a person’s sexual behaviour on the basis of their genes. While they did find five genetic variants associated with same-sex behaviour (and many others which may also be involved) at best these genetic differences could only account for between 8 and 25% of variation in same-sex sexual behaviour and could not be used to predict it.
The authors, from the Broad Institute of Harvard and MIT, analysed survey responses and performed genome-wide association studies (GWAS) on data from over 470,000 people in the UK Biobank and 23andMe.
The findings suggest that same-sex sexual behaviour is influenced by a complex mix of genetic and environmental influences like most human traits.
"Our findings provide insights into the biological underpinnings of same-sex sexual behavior," say the authors, "but [they] also underscore the importance of resisting simplistic conclusions because the behavioral phenotypes are complex, because our genetic insights are rudimentary, and because there is a long history of misusing genetic results for social purposes."
Since so many people believe that homosexuals are “born that way”, as Lady Gaga famously put it, the results of the research were widely reported.
The article was controversial even within the Broad Institute, which took the unusual step of publishing perspectives from employees criticising its own study. The authors sought the views of LGBTQIA+ advocacy groups about the language and presentation. Yet some researchers still questioned the need for the research. Meagan Olive, a research associate at the Broad Institute, wrote that it was “ultimately jeopardizing the perception and safety of the LGBTQIA+ community”.
Post-doc Joseph Vitti wrote: “Curiosity alone … seems insufficient justification to probe the genetic basis of a human behavioral trait — and, by extension, an identity — that demarcates a vulnerable population, let alone to do so in a high-impact scientific journal.”
One finding which is particularly sensitive is that same-sex sexual behaviour was positively genetically correlated with several psychiatric or mental health traits like depression and schizophrenia. It was not clear why – environmental factors like stigma could be responsible.
What the researchers fear is that the results of the study will be used to stoke hostility towards gays and lesbians. It also gives some support to advocates for reparative therapy. If homosexuality is not largely genetically-based, why is it wrong to try to modify sexual orientation, if a person requests help in doing so?
Michael Cook is editor of BioEdge
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