Having older brothers could increase the likelihood of being gay

Having older brothers could increase the likelihood of being gay

It's certainly not the first time scientists have noticed the pattern of gay men having older brothers, however this is the first time that a potential biological explanation has been discovered.

The research team suggested that with every male baby some women have, these antibodies build up in their bodies.

Researchers think it's possible that when a woman gets pregnant with her first boy, this Y-linked protein gets into her bloodstream. The researchers collected blood samples from 142 pregnant women and tested them for antibodies to a specific brain protein, known as NLGN4Y, which is only produced in males.

Bogaert and his team found the highest concentration of antibodies to NLGN4Y in women with gay younger sons with older brothers, compared with women who had no sons or only heterosexual sons.

Even so, that's not to say that men with more older brothers are automatically gay.

Of course, the findings don't mean that all men with older brothers will be gay, and the researchers admit that further studies are required, but it's intriguing nonetheless.

The team thought NLGN4Y would be an ideal candidate due to its significant part in how neurons communicate with one another, making it comparatively simple for antibodies to detect it.

"This is a very important study because it provides a plausible mechanism to explain the fraternal birth order effect, perhaps the most firmly established phenomenon related to human sexual orientation", says Marc Breedlove, professor of Neuroscience at Michigan State University, said, the New Scientist website reported.

The researchers analyzed plasma from mothers, half of whom had gay sons; women with no sons; and men in order to find antibodies for the protein NLGN4Y, which is found in men.

J. Michael Bailey, a professor in the Department of Psychology at Northwestern University, thinks the latest research is important. This effect has been termed the "fraternal birth order effect". They explain that there are several factors that determine the sexuality of an individual. At increased concentrations, there is a chance that their impact on the protein they target results in an adjustment in the development of the brain, which can influence sexual orientation.

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