But other scientists question whether these data can provide definitive conclusions.

The authors say their findings, published on 23 August in Nature Human Behaviour 1, could help to explain why genes that predispose people to homosexuality continue to be passed down. In a study of data from hundreds of thousands of people, researchers have now identified genetic patterns that could be associated with homosexual behaviour, and showed how these might also help people to find different-sex mates, and reproduce. Yet same-sex attraction is widespread in humans, and research suggests that it is partly genetic.

In theory, humans and other animals who are exclusively attracted to others of the same sex should be unlikely to produce many biological children, so any genes that predispose people to homosexuality would rarely be passed on to future generations. To evolutionary biologists, the genetics of homosexuality seems like a paradox. Credit: Piotr Lapinski/NurPhoto via Getty Same-sex attraction seems to be at least partly controlled by genetics.