A recent study has drawn controversy by implying genetic links between bisexuality in men and a propensity for risk-taking. This research on human sexual behavior, published in January in Science Advances, is an example of a genome-wide association study (GWAS). Such studies compare entire genome sequences from many people in a search for areas of overlap between genes and certain traits. The authors of the new study report that bisexual behavior in men is genetically distinct from exclusively same-sex behavior and suggest that the genes underpinning bisexual behavior are also linked to possessing an inclination for risk-taking and to having more children.
“The basic finding is that bisexual behavior and number of children are genetically positively correlated,” says senior study author Jianzhi Zhang, a professor of ecology and evolutionary biology at the University of Michigan. The study found that certain gene variants, or alleles, were more common in men with self-reported bisexual behavior. These same alleles were also associated with a self-reported inclination for risk-taking. Some men who reported exclusively opposite-sex behavior also carried the gene variants associated with bisexuality and risk-taking behavior; in these men, these genes were associated with reporting a higher number of sexual partners. In premodern societies, the study notes there was a strong correlation between higher number of sexual partners and fathering more children. The researchers posited that these correlations could be an evolutionary explanation for why bisexual alleles and behavior persist in the human population.
Zhang and his co-author based the findings on data on about 450,000 people from the UK Biobank, a database of participants’ genetic information and self-reported answers to survey questions that is commonly used in GWASs. Starting in 2006, UK Biobank recruited participants who lived in the U.K. and were between 40 and 69 years old. The new study, like many…
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