I'm not certain how dancing or playing with cars is anything but cultural. I mean, aren't these products of years of culture, including the gender roles assigned to them? What makes dancing girly and cars boyish?

"The sexes are hard wired totally differently."

The thing is, I can get behind this statement. If you zoom out further, and say, "Boys are different from girls." you can even say, "duh".

I'm pragmatic; I would accept biological evidence suggesting that men are more biologically inclined to be programmers. But how likely is it that that gap reflects the gender ratio that we see in software developers today?

It's possible, but I think it's unlikely.

I think that a much LARGER force is the perpetuation through behaviors like this presentation that developing software is a "boys only" club. If women want to play, they have to "man up". Creating a female-unfriendly culture is still gender discrimination, even though there's no one person doing it.