outerplaces.com
One of the most controversial questions of our time may finally have an answer: Is homosexuality something you’re born with, or a choice?
Cross-cultural studies like the one published by the Archives of Sexual Behavior have looked into homosexuality in places as disparate as Samoa and Mexico, but the genetic dimension of homosexuality has remained unclear.
A new study from the decorated Brock University, however, suggests that specific factors during prenatal development have a strong influence on whether or not males become homosexual.
The study looked into a phenomenon called the « older brother effect, » in which male siblings with older brothers seemed to have a higher chance of being homosexual.
To look for potential biological factors, researchers studied 16 women without male children, 72 mothers with heterosexual male children, 31 mothers of homosexual male children with no older male siblings, 23 mothers of homosexual male children with older male siblings, and a control group of 12 males.
The study focused specifically on two proteins, NLGN4Y and PCDH11Y, both of which are found only in males and are present in the fetal development of male brains.
According to Bogaert, NLGN4Y (and a mother’s immunological response to it) may be a key factor in determining whether a male child will be homosexual.
« 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. 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, » said Bogaert.
What all this suggests is that the « older brother effect » is real, and that its cause may be based in immunology, rather than in genetics.
In the bigger picture, it’s a strong case for the hypothesis that homosexuality is determined (at least in males) before the child is born.