Dr. Marc Breedlove

It's a fascinating idea, and it also gets at that same theme that I mentioned before.

There are lots of different developmental pathways to end up being gay or to end up being straight, and there isn't going to be one cause.

of anything in human behavior and certainly not of sexual orientation.

But I think the evidence is looking pretty strong that for women at least, prenatal testosterone does have a say and we know that in men, the mother's body has a say in whether they're going to be gay or straight when they grow up.

Yeah, I mean, Ray's looked at that very carefully.

And so older sisters don't matter, and neither do younger sisters.

And here's the other thing, younger brothers don't matter, right?

So no matter how many younger brothers you have, that doesn't change your odds of being gay when you grow up.

So that's why I say it's got to be the mother's body

that is remembering, and it doesn't seem to be socially mediated.

It is, you know, independent of that.

It is nature having its say.

No, I didn't know that, but I can see... I mean, you have to remember, actually, there are several different genetic mutations...

along the pathway of making adrenal steroids that can go wrong.

And so there are several steps that have to be there for them to make adrenal steroids.

So number one, there's more than one site where the mutation would be carried.

And of course, the heterozygotes may have no symptoms whatsoever.

And so they may reproduce just fine.

Another reason why the carriers are so common is because typically there's no phenotype, or if there is, it's subtle and so it doesn't come to the attention of any physicians.

It's only when two defective copies of the gene come together in one offspring that there's no adrenal steroid production at all, and then things happen enough to get the attention of the doctors.