A team of researchers from the University of Toronto and the University of Lethbridge has found evidence showing that Men with an older brother are more likely to be homosexual than men without.
In your study, published in the magazine Proceedings of the Royal Society B, comes to provide more data regarding the reasons, still unknown, for the origins of homosexuality.
Question of antibodies?
The study cited analyzed data from 10 unrelated studies that included sexual orientation for 5,400 men and also information on siblings, finding that those who had an older brother were 38 percent more likely to be homosexual than those who did not have an older brother.
They also discovered that The more older brothers a man had, the more likely he was to be gay.: Having three older brothers, for example, doubled the odds of a man being gay.
But the same could not be said of women. The researchers couldn't find any pattern in siblings, male or female, that changed the likelihood that a woman would be gay.
The researchers couldn't determine why birth order affects the likelihood of being gay, but they suggest it's possible that the mother's immune response having a male child has a subsequent impact on the babies born thereafter.
The theory, called maternal immune hypothesis, suggests that when a woman gives birth to a male baby, her body produces antibodies in response. The theory then suggests that the antibodies produced remain in the woman's body and somehow they reach the brains of future baby boys.
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The news
According to a study, there is a correlation between having an older brother and being gay
was originally published in
Xataka Science
by
Sergio Parra
.