Men With Older Brothers ‘More Likely To Be Gay’, Study Says

People have often wondered what governs the sexuality of the estimated 10 percent of people who make up the gay community.

 In a ground-breaking study, scientists have tentatively offered a possible explanation based in biology – or nature – rather than nurture.

The research was inspired by one of the great unexplained quirks of biology: the more older brothers a man has, the more likely he is to be gay, apparently.

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Now scientists claim having a male child triggers an immune reaction in the mother that can alter the brain of the growing baby.

The authors of the report, led by Toronto University, published their study in Proceedings of the National Academy of Sciences and were quick to stress this is one of many factors in what determines a person’s sexuality.

 They wrote:

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They claim:

The research hoped to explain what they call ‘one of the most reliable correlates of male homosexuality: older brothers’, which has seen the 3 per cent chance of a male son being gay doubling to six per cent if he has brothers.

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Boys are made up of an X and Y chromosome, whereas girls have two X chromosomes.

When a mother is pregnant with her first baby boy, her body reacts against the Y chromosome, and creates a large quantity of the antibody called anti-NLGN4Y.

These antibodies can affect the brain development in later male children, which the study authors have inferred to ‘suggest an association’ with the brain structure, and ‘subsequent sexual orientation in male offspring’.

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They add:

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However, they were careful to admit the study isn’t proof. Thus, the scientific endeavour to decipher what ‘makes’ a person heterosexual or homosexual will continue.

It is worth noting, they say, a fraternal birth order (FBO) effect exists in the sexual orientation of men, but not of women.

Presumably, members of the gay community will get on with their lives, hopefully able to avoid being put under the microscope for their sexuality.