Homosexuality: Genes related to same-sex behavior are also found in heterosexual people, according to the study

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One study has found that genes related to same-sex sexual behavior are also found in heterosexual people, where they are associated with having more sexual partners.

This mating advantage could offset the “loss” of reproduction between gay individuals and explain the persistence of these genes throughout human evolution.

This is the conclusion of researchers at the University of Queensland, who studied the genomes of 477,522 people, both in the United Kingdom and the United States.

However, they warned that more research will be needed to confirm the results, given the small size of the genetic differences studied and the limited range of samples.

One study found that genes related to same-sex sexual behavior (pictured) are also found in heterosexual people, where they are associated with having more sexual partners (pictured)

One study found that genes related to same-sex sexual behavior (pictured) are also found in heterosexual people, where they are associated with having more sexual partners (pictured)

Researchers led by the University of Queensland, who studied the genomes of 477,522 people, both in the UK and the US, using data from the UK Biobank and 23andMe

Researchers led by the University of Queensland, who studied the genomes of 477,522 people, both in the UK and the US, using data from the UK Biobank and 23andMe

OTHER THEORIES

The new hypothesis raised by Professor Zietsch and colleagues is not the only one that offers an explanation of how to reconcile a genetic basis of homosexual behavior with evolutionary theory.

A main idea is based on the notion of selection of relatives, and is sometimes called the “gay uncle” hypothesis.

According to this theory, homosexual individuals support their relatives, such as helping to provide resources, food, and protection, thus ensuring the continuity of their family’s genes, at the expense of their own.

Thus, from an evolutionary perspective, the broader benefits of same-sex sexual behavior could outweigh the apparent drawbacks.

The research was conducted by psychologist Brendan Zietsch of the University of Queensland, Australia, and colleagues.

“Sexual behavior between people of the same sex is heritable, confers no immediate or direct reproductive benefit of survival, and may divert the mating effort from reproductive opportunities,” the researchers wrote in their article.

“This presents a Darwinian paradox: why has same-sex sexual behavior been maintained despite the apparent selection against it?”

In its study, the team analyzed the genomes of a total of 477,522 individuals in the United Kingdom and the United States, comparing those who had had same-sex sexual behaviors with those who had sex exclusively with members of the opposite sex. .

Data from the study were collected both in the UK Biobank (a large-scale database containing detailed genetic and health information on half a million participants), and in the records of personal genomics company 23andMe.

Participants in the UK Biobank study also provided information on the total number of sexual partners they had throughout their lives.

From this, the researchers examined among the genomes of 358,426 heterosexual subjects the associations between previously identified genes related to same-sex sexual behavior and the number of sexual partners each person reported.

The researchers wrote that “we show that, among individuals of sexual behavior of the opposite sex, the genetic effects associated with same-sex sexual behavior are associated with having more sexual partners of the opposite sex.”

“Computer simulations suggest that this mating advantage for alleles associated with same-sex sexual behavior could help explain how it has evolved,” they added.

In our past, having a larger number of sexual partners, the team explained, would probably have led to more children, preferably passing on genes that can also cause same-sex attraction for generations in a process of natural selection. .

“Computer simulations suggest that this mating advantage for alleles associated with same-sex sexual behavior could help explain how it has evolved,” the researchers explained in their paper. In the picture: a gay couple (stock image)

The team has warned, however, that its study includes several limitations and that, as a result, the findings should be interpreted with caution.

The genetic data analyzed in the study, they noted, were only collected from individuals of European descent, meaning that they capture only a fraction of human genetic and behavioral diversity.

Since the practice of same-sex sexual behavior and the number of opposite-sex sexual partners they have are influenced by social forces, this data bias is likely to affect outcomes to an uncertain degree.

The genetic differences identified were also small, spread throughout the human genome, and probably capture only a small portion of the heritability of same-sex sexual behavior.

In addition, according to researchers, the number of opposite-sex sexual couples reported by individuals today is not necessarily associated with a similar reproductive advantage in humanity’s evolutionary past.

The full findings of the study were published in the journal Nature Human Behavior.

THERE IS NO SINGLE “GAY GEN”

For some time now, scientists have been trying to quantify the extent to which genetic and non-genetic (or environmental) factors affect a person’s preference for same-sex relationships.

Several studies have suggested that genetic factors were complex, but their relatively small scales made it difficult to draw reliable conclusions.

In one study, researchers used data from more than 470,000 people, more than 100 times more than previous work.

They confirmed that homosexuality comes from genetic and environmental factors.

Instead of being a single “gay gene,” however, the team found thousands of sites (or loci) in the genome that appear to play a role in sexuality.

Only five of these had a “significant” impact and, combined, all factors accounted for only 8–25% of the variation in sexual attraction between different people.

The factors at play are so complex that it is impossible to predict from a person’s DNA whether they are attracted to members of the same sex or not.

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