Wow, a comment so long it needs a summary. Here's the condensed version: It takes lots of practice to be a good hacker. Young (HS) girls have more pressure to be popular, which takes time away from recreational hacking. Older (college and above) girls are at a disadvantage because they didn't start young. They get discouraged and major in something else. Repeat over a statistically significant population and voila! Also, kids haven't lived long enough to accrue the practice.

Long version:

I'll bite. While we can't how much of hacking (or anything) is because of innate abilities and how much is from practice, most of the research I've read says that excellence in any field comes from sustained (years) of meaningful practice. This means that even if you're really smart, you need to spend lots of time to be really good. And no matter how smart you are, if you don't spend time on something, you won't accidentally get good at it. (nothing controversial so far)

So I'll make the claim that if men are statistically better hackers, it's because they're statistically more likely to have spent more time hacking (solve the children question). It also explains why people in their 20s who have hacked meaningful projects are better than older, more "experienced" 9-to-5ers who do the same types of things over and over again and don't expand their knowledge and experience.

As for women, I would say that women statistically find greater rewards for pursuing other interests than computers. More to the point, I would say that there is more pressure for girls to be attractive and popular than for guys, and greater consequences for not being so. This both cultural and biological, and I believe that much of it is because most girls have to be asked out by guys. So, average girl needs to be popular, and as pg explained in "Why Nerds are Unpopular" (http://www.paulgraham.com/nerds.html), being popular is a lot of work. So much work that it crowds out everything else.

Fast forward to college, and girls that would then want to learn computers are at a disadvantage to guys that have been hacking for years because they didn't bother taking the time to be popular. They're mentally capable but years behind in practice, and it makes them feel inadequate, so they choose a different major. Note: this also works for guys that didn't hack in high school - they're at a disadvantage to those who did, no matter how smart they are. Most people don't like discouragement so they go somewhere where that makes them feel better.

Thoughts?