His work claims smoking and drinking have the greatest effect on IQ while synthetic hormones and smoking lead to “the likelihood of girls being lesbians or bisexual.”
The Telegraph reports Swaab also believes a boy with several older brothers has a higher chance of being gay.
And there’s more.
“Pregnant women suffering from stress are also more likely to have homosexual children of both genders because their raised level of the stress hormone cortisol affects the production of fetal sex hormones,” he added.
The professor blames increased autism rates on areas with high pollution levels.
Swaab admits that genetics remain the biggest factor in our health but points out his research means more attention should be paid to development of the brain during pregnancy.