A mother’s immune system could influence sons’ sexual orientation | December 13, 2017 Issue – Vol. 95 Issue 49

About 10 years ago, Bogaert reported data pointing to a biological origin for the phenomenon, instead of a social one. The findings showed that growing up with older step or adopted brothers doesn’t increase a man’s likelihood of being gay, but having older biological brothers who grew up elsewhere does. “It really suggested that there was a before-birth effect and that childhood or adolescence was not playing a role,” Bogaert says.

... read more at: https://cen.acs.org/articles/95/i49/mothers-immune-system-influence-sonssexual.html