Genomic evidence consistent with antagonistic pleiotropy may help explain the evolutionary maintenance of non-heterosexual behaviour in humans

Abstract: Non-heterosexual behaviour in humans is genetically influenced, confers no obvious reproductive or survival benefit, and can divert mating effort away from reproductive opportunities. This presents a Darwinian paradox: why has non-heterosexual behaviour been maintained in the population despite apparent selection against it? Here we show that genetic effects associated with non-heterosexual behaviour are, in heterosexuals, associated with greater mating success. We show, in a genome-wide association study (GWAS) in 477,522 individuals from the UK and USA, that the combined effect of many genetic variants with small effect predispose to non-heterosexual behaviour. Alleles that predisposed to non-heterosexual behaviour were associated in heterosexuals with having more lifetime opposite-sex partners and, in heterosexual men, with being more physically attractive. Our results suggest that genetic variants that predispose to non-heterosexual behaviour confer a mating advantage to heterosexual carriers, which could help explain why non-heterosexual behaviour has been evolutionarily maintained in the population.

Bio:Brendan is an ARC Future Fellow in UQ’s School of Psychology and is director of The Centre for Psychology and Evolution. His work combines behavioural genetics and evolutionary psychology and covers a range of topics in these fields.

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