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It turns out that there may be some genetic and evolutionary factors afoot when it comes to bisexuality — but naturally, there are ethical concerns about such bold statements.
As Science magazine reports, this new research looking into the genetics of bisexuality suggests more of a propensity for risk-taking and is distinct from the genes that may underly homosexual behavior. If that sentence raises alarm bells, you’re not alone.
Published in the journal Science Advances, even the name of the paper itself, “Genetic variants underlying human bisexual behavior are reproductively advantageous,” harkens back to the old nature-versus-nurture arguments that most people, queer or otherwise, would rather forget.
Despite the face-value implications, however, the content of the study is pretty fascinating.
Jianzhi Zhang and Siliang Song, the evolutionary geneticist duo out of the University of Michigan who coauthored the paper together, insist that their findings need not be painted with the brush of morality because, as Zhang put it, the association they found between bisexuality and risk-taking behavior “is an empirical observation.”
“We hold no moral judgement on risk-taking and believe [it] has pros and cons (depending on the situation), as almost any trait,” Zhang told Science. “This is partly a biological question, so we should understand it.”
Zhang and Song examined data from the UK Biobank, the giant genetic database compiled with the help of 23andMe, and deviated in one key way from a groundbreaking 2019 study about the genetics of same-sex behaviors: they decoupled self-reported homosexual and bisexual behaviors, which until now had been lumped together under the “same-sex sex” umbrella.
Using some statistical and algorithmic magic, the UM team found that although the genetic variants between bisexual behavior and homosexual behavior are related, they’re still distinct from one another.
What’s more, the risk-taking aspect of bisexual behavior was apparent in men, but not in women — and, strangely enough, the risk-taking genetic variants also seemed to account for a higher chance of having offspring, too.
The conclusion drawn here is that bisexuality has evolutionary benefits. But as behavioral geneticist Andrea Camperio Ciani of the University of Padova in Italy pointed out to Science, it still doesn’t do much to explain what evolutionary purpose, if any, same-sex behavior might carry.
“[Gay people] have been everywhere in every nation,” he explained. “Always at a low frequency, but everywhere.”
Beyond the murkiness on the evolutionary side of things, there’s also the data itself. The paper’s results are based on self-reported sexual behaviors rather than orientation or identity. And as Yale geneticist Steven Reilly cautioned Science, the UK Biobank’s respondents skew older and may have been describing encounters or behaviors that took place when homosexuality was still illegal and stigma-laden.
Lastly, of course, is the stigma such research could bring about in today’s world, where bisexuality is much more accepted than it was in the past but is still very misunderstood and maligned, even in queer communities.
Purdue sociogenomicist Robbee Wedow, who coauthored the 2019 study finding genetic variants associated with homosexuality, went so far as to say that the new research’s focus on bisexuality and evolutionary fitness “is not only incorrect, but — I would say — dangerous.”
Zhang, on his end, rejects that characterization outright.
“Many studies that were once considered dangerous propelled the progress of science, technology, and society,” the researcher told Science.
More on queer procreation: Scientists Find Kids With Gay Dads Are Doing Better Than Kids With Straight Dads
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