Straight men with 'bisexual genes' have more children because the variations are linked to risk-taking, study claims

Bisexuality may have emerged in humans for a good reason: to help men have more children.

Looking at it only from an evolutionary point of view, the existence of a “bisexual gene” has confused some scientists.

If we are genetically programmed to keep humanity alive by having children, and same-sex encounters did not produce children before IVF became possible, some wondered why bisexuality existed.

But a study has found that “bisexual genes” may play a different role: When found in heterosexual men, those men have more children.

The study looked at more than 450,000 people in Britain, including heterosexual men who showed small genetic differences that are more common in bisexual men.

These men were not actually bisexual, but because they had genes linked to bisexuality, they had more children on average than other heterosexual men.

Researchers also found that straight men with bisexual genes were more likely to say they took risks in life – so they may have had more sexual partners or unprotected sex, leading to a greater number of children.

If genetic variations linked to bisexuality lead to more children for men, this could explain why they exist and are passed down from generation to generation.

However, the researchers emphasize that the findings “mainly contribute to the diversity, richness and understanding of human sexuality,” adding: “They are in no way intended to suggest or endorse discrimination.”

The study found no link between genes linked to bisexuality in women and the number of children they had.

Professor Jianzhi Zhang, senior author of the study from the University of Michigan, said: 'Although bisexual men have fewer children on average than heterosexual men, heterosexual men who carry bisexual genes have more children than those without such genes.

'This could potentially keep bisexual genes in the population.

“As for why heterosexual men with bisexual genes have more children than those without such genes, we found that heterosexual men with bisexual genes are more willing to take risks and that risk taking is correlated with having more children.”

The study, published in the journal Science Advances, looked at adults involved in the UK Biobank health study whose genes had been sequenced.

This helped identify people with genetic variations linked to bisexuality, as they are more commonly seen in people who have sex with both men and women.

Overall, heterosexual people in the study had an average of about 1.9 children, while bisexual and gay people had fewer children.

However, an interesting finding emerged when researchers looked only at heterosexual men who carried bisexual genes and who were not in fact bisexual.

These men had more children and were more likely to answer yes to the question, “Would you describe yourself as a risk taker?”

Although the question about risk-taking did not specify the type of risk, it is likely that this would include unprotected sex and promiscuity, which the authors say could lead to more children.