Is homosexuality caused by a single gene?

Monday, May 2, 2022
By Jacob Alabab-Moser

While there may be a genetic component to homosexuality, same-sex sexual behavior is not determined by a single gene.

The largest study conducted on homosexuality and genetics to date, published in Science in 2019, identified five spots on the human genome that are linked to same-sex sexual behaviour, but cautioned that none of the markers are reliable enough to predict someone’s sexuality. After comparing the genomes and sexual behaviors of nearly half a million people, authors estimated that genetics explains 8% to 25% of homosexuality, with the rest influenced by environmental and cultural factors. The study did not find that homosexuality was associated with a stretching of DNA on the X chromosome, as a small study from 1993 had.

A study published in Nature in 2021 suggested that the mating advantages of risk-taking behavior, which authors found to be genetically correlated with same-sex sexual behavior, could explain how homosexuality persisted as a trait despite contradicting the evolutionary principle of reproduction.

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