Jun 27 2006
Older Brothers and Sexual Orientation
According to findings reported by ScientificAmerican.com, “Having Older Brothers Increases a Man’s Odds of Being Gay.”
The number of biological older brothers a boy’s mother has carried–whether they live with him in the same household or not–affects his chances of being gay. The findings, reported this week in the Proceedings of the National Academy of Sciences, by Anthony Bogaert of Brock University, lend credence to the theory that it’s not the social or rearing factors that influence a man’s sexual orientation, but rather prenatal mechanisms that begin in the womb.
[...]
The fact that the common denominator between the older and younger biological brothers is the mother hints at a prenatal influence on sexual orientation. What it could be is still a mystery. But one theory suggests that after delivering a boy, a woman’s immune system produces antibodies to male-specific proteins. During subsequent pregnancies the mother’s placenta may deliver the antibodies to the fetus, possibly affecting its development.
Booker Rising adds:
First, he found that only the number of biological older brothers predicted sexual orientation in men–even when the number of non-biological older brothers was significantly higher. Second, his study showed that the amount of time reared with older brothers–either related or not–did not predict a young boy’s becoming homosexual. Professor Bogaert discovered that even if a young man did not grow up in the same house as his older brothers, the fact that he had older biological brothers increased his odds of being gay.
Spare Change has doubts about the study:
944 test subjects, out of a global population of 3 billion. And from that an unnumbered subpopulation of men with older brothers. And from that subpopulation, another subpopulation of homosexual men were extracted and examined. Add in no real data, and ignore any number of other important variables such as whether or not there was a dad in the home, whether the home life was healthy, violent, or in some other way dysfunctional, and then wildly interpret the flawed deductive reasoning
