Nalendwa
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- Aug 9, 2016
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Earlier studies have noticed that gay men often have older brothers.
Scientists have noticed this pattern in previous research, but now they think they have a biological explanation as to why, and it starts long before birth. The results were published in thejournal PNAS on Monday.
The researchers say that if their findings can be replicated, we may know at least one of the biological reasons some men are gay.
Many factors may determine someone's sexual orientation, but in this case, researchers noticed a pattern that may be linked to something that happens in the womb. The phenomenon is related to a protein linked to the Y chromosome (which women do not have) that is important to male brain development.
Researchers think it's possible that when a woman gets pregnant with her first boy, this Y-linked protein gets into her bloodstream. The mother's body recognizes the protein as a foreign substance, and herimmune system responds, creating antibodies. If enough of these antibodies build up in the woman's body and she gets pregnant with another a boy, they can cross the placental barrier and enter the brain of the second male fetus.
"That may alter the functions in the brain, changing the direction of how the male fetus may later develop their sense of attraction," said study author Anthony Bogaert, a Canadian psychologist and professor in the departments of psychology and community health sciences at Brock University.
Earlier research has shown that the more older brothers a boy has, the more of a chance that boy will be attracted to men. A 2006 study showed that with each brother, the chance that a man will be gay goes up by about a third, but the researchers didn't determine why that was.
Bogaert and his co-authors tested a small group of 142 women and 12 men ages 18 to 80 and found a higher concentration of antibodies to the protein, known as NLGN4Y, in blood samples from women than from men. They found the highest concentration of antibodies to the protein in women with gay younger sons who had older brothers, compared with women who had no sons or who had given birth to only heterosexual boys..
Having older brothers tied to being gay, if you're a guy - CNN
