Scientists have finally worked out why younger brothers are more likely to be gay.
Researchers at Brock University, Canada, have found that women who get pregnant with boys multiple times slowly build up antibodies that affect their babies while they’re carrying.
The antibodies, which are made by the body in response to proteins present in the brains of males, can supposedly lead to changes in brain development which could have an impact on sexual orientation.
“It seems that some women during their first male pregnancy, or just after their first male birth, begin to detect this foreign substance (the NLGN4Y protein) and start to develop an immune response,” said lead researcher Tony Bogaert.
“And then later, with further male pregnancies, the high levels of antibodies directed toward this substance may change brain development in these later born males.
“The implications of this study, especially if and when it is replicated by an independent team, are profound,” he continued.
It’s a big step forward, because it helps to prove that there is a strong biological link to sexuality.
“Along with more deeply understanding the exact origin of the older brother effect, it helps solidify the idea that, at least in men, there’s a strong biological basis to sexual orientation.
“This is the culmination of more than 20 years of research where we started looking at the older brother, or fraternal birth order, effect. The current study adds to the growing scientific consensus that homosexuality is not a choice, but rather an innate predisposition.”
Meanwhile, scientists have been searching for a so-called ‘gay gene’ and studying how sexual orientation is partly biologically determined.
Now, a new study has identified what might be two genes which have an impact on someone’s sexuality.