A new book from neurobiologist Dick Swaab (yes, that is really his name) is stirring up controversy with claims that smoking, hormones, and stress during pregnancy are causing more children to be born gay. In We Are Our Brains, the Dutch author and professor writes that "factors ranging from taking synthetic hormones to leading a stressful life" can hardwire homosexuality into children in the womb.
Swaab's assertion is based in part on an old study of women who took synthetic estrogen between 1939 and 1960 (it showed these women had an atypically high proportion of daughters who grew up to identify as either lesbian or bisexual). He's extrapolating on the other factors, and "no study has shown a correlation between cigarette smoking during pregnancy and the sexuality of a child," Medical Daily notes. Swaab says that sexuality is wholly determined prenatally. “Children brought up by lesbians aren’t more likely to be homosexual," Swaab told the Daily Mail , adding that there's no evidence that homosexuality is a "lifestyle choice."
Swaab's claims have a lot of people fuming (or at least eye rolling), given that this assertion makes it seem as though homosexuality is some sort of punishment for bad behavior. But, some gay rights advocates actually welcome Swaab's point of view because it's all nature, no nurture. Gay rights campaigner Peter Tatchell told the Daily Mail “It is a slap down for religious and political homophobes. If being gay is mostly or wholly determined by biological factors prior to birth, it is immoral to condemn or discriminate against lesbians and gay men."
Either way, Swaab's theories on how a mother's behavior effects a child's sexuality seem to have little to back them up, outside of general studies about prenatal brain development. "There does not seem to be a shred of evidence to support the idea that a mother’s lifestyle changes a child’s sexuality," Ben Summerskill, CEO of gay rights organization Stonewall, told the Mail. "Our feeling is that sexuality is probably is caused by genetic inclination, but until the evidence is there, nobody can say either way."