Study claims men with older brothers have higher chance of being gay

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A new study has claimed to have discovered why men with older brothers have an increased chance of being gay.

But other scientists are concerned about what effect this type of study has on the world at large.

The research, which examined around 142 women and 12 men, found a protein associated with the Y chromosome entered a woman's body after her first pregnancy with a boy.

Her body creates antibodies against it which, if she gets pregnant with another boy, can cross the placental barrier and enter the foetus' brain.

Canadian psychologist and researcher Dr Anthony Bogaert, the study's lead author, said this can "change the direction" of how the male foetus develops their sense of attraction.

It comes after a wider study was released last week studying the genomes of around 2000 European men, including around 1000 straight men and 1000 gay men.

However research into a potential "gay gene" has a wider impact on soceity, Dr Ilan Dar-Nimrod from University of Sydney's School of Psychology warned.

"Some research has found that while learning about genetic attribution for homosexuality can make people more accepting of gay individuals, it can also lead people with anti-gay attitudes to polarise their views rather than mitigate them," he said.

"In this instance it results in a heterosexual person feeling a clear 'us' and 'them' that leads to distancing from 'them' (i.e. gay people). Such a feeling may fuel prejudice."

Dr Dar-Nimrod said it's not just straight people affected by this distinction.

"While the naturalness of sexual orientation (e.g. genetic basis) is associated with decreased internalised homophobia, the feeling that the groups (i.e. heterosexual and gay people) are distinct is associated with increased internalised homophobia."

Dr Nina McCarthy, from the University of Western Australia's School of Biomedical Sciences, said it's unlikely a "gay gene" would ever be discovered, as it's more likely homosexuality is a result of a combination of biological and environmental factors.

"The justification for the research is unclear to me," she said, explaining that similar studies are often carried out to try and find a cure for an illness.

"As homosexuality is emphatically not an illness, the potential benefits of trying to better understand the underlying biology of homosexuality remain (to me) a little elusive."

The study released last week has also been criticised for having a small sample size, of around 2000 participants compared to similar genome studies with more than 100,000 participants.

Newshub.