Director of the Charles & Barbara Duboc Cardio Health & Wellness Center at Saint Luke's Mid America Heart Institute
Pro to the question "Is Sexual Orientation Determined at Birth?"
"You probably have gay genes in your DNA. But unless they were turned on in your mother's womb, they remained coiled up and silent... So what conditions in the uterus turn on those gay genes? So for a male, your chances of homosexuality increase in proportion to the number of previous baby boys who inhabited your mother's uterus. So for every older biological brother you have, your chances of being born gay go up 33%. Long before we invented the pill, nature devised homosexuality as a prescription for birth control. After four straight heterosexual males, nature says: 'enough already!', and the mom's immune system switches on the epigenetic switch so a gay male is born into the family. This one will be not be overburdening the clan with yet more mouths to feed in the next generation. Sometimes more isn't better. And he's not going to be killing his brother in a fight over who gets the girl...
Another gene, this one on the X chromosome, is called a male loving gene. Because when it shows up in a female, she tends to mate early and have a lot of kids. But when the male loving gene shows up in a male, it predisposes to homosexuality. So this is another gene that balances a family destined to have a large brood of kids and grandkids with an occasional gay son whose natural tendency to promote togetherness could improve the chances of survival for the whole family...
I have no doubt that female homosexuality is also a natural variation that is advantageous for the family and the community."
TEDx Talks, "Homosexuality: It's about Survival - Not Sex | James O'Keefe | TEDxTallaght," YouTube.com, Nov. 15, 2016