Although most biologists suspect there’s a genetic element to human sexuality, that suspicion poses a serious conundrum: What possible evolutionary advantage would homosexuality carry given that gay people are less likely to have children? In line with Darwin’s theory of evolution, wouldn’t any “gay genes” have died out over successive generations?
To make a long story short, geneticists suspect genes linked to same-sex attraction may be linked to other factors that increase someone’s fitness.
“Fitness” in this sense relates to how likely you are to pass on your genes to successive generations — not necessarily how many squats you can do at the gym.
How about we take this to the next level?
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Now, a new study has attempted to throw some light on the matter. It suggests it’s related to bisexuality.
A new paper published this week in Science Advances, claims that genetic factors linked to bisexuality have traditionally been linked to men who have a greater appetite for risk and have more children.
Risk takers
The research drew upon the UK Biobank, which holds 450,000 genetic samples linked to accompanying behavioral surveys. In short, it has the genetic codes for a large number of gay and bisexual men and women.
Previous research points to a link between genetics and risk-taking behavior in men. This new study goes further, saying there’s a link between risk-taking, bisexual behavior, and an increase in offspring.
How this might influence people who are exclusively gay is unclear. The same study says gay and bisexual people are genetically distinct.
The data shows men who engage in exclusively opposite-sex couplings have the greatest number of children, followed by those who are bisexual and then those who are gay.
However, bisexual men also showed a great appetite for risk-taking and were likely to have more sexual partners. This means they’re more likely to father more than one child, which means their genes persist and do not die out.
Are you following?
“People who carry bisexual genes have more children,” lead author Jianzhi Zhang of the University of Michigan told The Hill. “And the reason they have more children is because the so-called the bisexual genes [mean that they] are willing to take more risks.”
Contraception cuts birth rate
However, that throws up another mystery.
In earlier centuries, having more sexual partners tended to mean fathering more children. Those differences disappeared in the 1960s with the arrival of the contraceptive pill. Having a large number of opposite-sex partners no longer means having more kids.
The authors also acknowledge this. They point to the fact that societal pressure has changed and people now feel more able to be out about who they are.
“We predict that for exclusive same-sex behavior [genetic alleles], they will decline in frequency over time in the future,” Zhang told The Hill. “But because same-sex behavior is influenced more by the environment than by genes, whether the proportion of people in this society will increase or decrease is unknown.”
In a further comment to Queerty, he said, “It is likely that, as society becomes more open to sexual minorities, more people are willing to perform same sex behavior and more people with same sex behavior are willing to come out.”
He added that for the purposes of research, they consider same-sex attraction and same-sex behavior separately.
“We studied same sex behavior rather than attraction. Same sex behavior is influenced more by the environment than by genes, and I believe this is a consensus among biologists. I do not know the situation about same sex attraction.”
The authors add that one of the limitations of their own study is that it drew exclusively on the UK Biobank. This is primarily British people of European ancestry: “Consequently, our results may or may not represent a general pattern across populations with diverse cultural, social, economic, and/or political environments.”
This article was update 01.06.24 to include comment from the study’s co-author.
