February 25, 2015

expert reaction to paper on genetic factors in sexual orientation and number of partners in females

A paper published in the Journal of Sexual Medicine has attempted to analyse sexual characteristics in female twins, with particular regard to homosexuality. They found that in their cohort of British twins, “masculine” women were more likely to be nonheterosexual and to report more sexual partners.

Dr Simon Underdown, Principal Lecturer in Biological Anthropology, Oxford Brookes University, said:

“Previous studies have examined the relationship between homosexuality and genetics and suggested a wide range of differing results. This paper makes some mistaken assumptions about how evolution works. While homosexuality is relatively common in human populations it does not biologically prevent breeding from taking place and hence genes being passed on. Gay people can, and do, have children which means that there is no strong selective pressure that would act against homosexuality in the first place and as such would not seriously impact on reproductive fitness. In non-human species the pattern is relatively simple but gets much more complicated when trying to explore the culturally highly adaptable Homo sapiens who have developed a bewildering number of ways to cheat evolution. While there may be, on paper, a genetic link between sexuality and number of partners for homosexual women, realistically it is not possible to control for the huge impact environmental effects will play. ”

‘Common Genetic Factors among Sexual Orientation, Gender Nonconformity, and Number of Sex Partners in Female Twins: Implications for the Evolution of Homosexuality’ by Rahman et al. published in Journal of Sexual Medicine on Wednesday 25th February. 

Declared interests

None declared