Carole Hooven, Ph.D.

They've gotten an IRB for a lot of incredible studies that are... Would never be done today.

Super rigorous and gold standard.

So yes, thank you for that last piece.

That's very important.

So the production of testosterone in the testes, this is really important and just fundamental to understanding sex differences.

It's not that we have so many different genes.

So at the same time, I should say, we're learning more about the role of the 70 to 100 genes on the Y chromosome, many of which are crucial for typical development of male reproduction and reproductive function.

But also it appears that there's some role even prior to the production and action of testosterone on the body and brain.

There may be early expression of genes on the Y chromosome that act in the brain to shape later patterns of behavior.

There's a lot of work going on there to understand that.

There are genetic differences.

And I also want to say that the genetic differences don't just stop at the differences with those genes on the Y. All the other genes are the same except for the sex chromosomes.

But having one X versus two Xs makes a huge difference.

It's extremely important.

So people think that females completely silence one of their X chromosomes in each cell, which is something that basically does happen so that we don't have a double dose of X chromosome genes compared to males.

So that's something called a bar body.

Yes, that's right.

And we can talk about Turner syndrome.

But something like 20%, and here someone might correct me, but I think around 20% of the genes...

on the silenced X escape inactivation.