Neale stressed that the scale of the influence of non-genetic factors, complexities of sexual behaviour, and difficulties in precisely measuring the size of any variant’s effects, means it is not possible to use genetic information to predict whether an individual will have same-sex partners.
The team believe one, found only in men, might be involved in sex hormone regulation, not least because it is linked to male-pattern balding.Įven taken together, though, these five genetic variants explain less than 1% of the variation in same-sex behaviour among participants – suggesting many other variants are involved, each playing a very small role.
Researchers found five genetic variants – tiny differences in DNA – that showed a clear link to same-sex sexual behaviour, two in both men and women, two found only in men and one found only in women. The team then looked at which genetic variants might be behind the link, using data from more than 400,000 participants in the UK Biobank project and more than 68,000 individuals whose data was collected by the company 23andMe. “For example, it is thought that non-genetic factors before birth, such as the hormonal environment in the womb, also play an important role,” he told the Guardian. That, they say, chimes with previous twin studies that put the figure at about 30% to 50%.ĭr Brendan Zietsch, co-author of the research from the University of Queensland in Australia, said that does not mean the rest is due to upbringing or culture. The team stress that they did not focus on identity or orientation, and did not include transgender individuals.īy looking at sexual behaviour and relatedness of individuals, they estimated that about a third of the variation in same-sex behaviour is explained by genetics. In the first part of the study, they looked at data from about 500,000 individuals collected as part of the UK Biobank project: about 4% of men and nearly 3% of women said they had ever had a same-sex sexual experience.