Computer science stereotypes revolve around geek culture. That culture is very male dominated, so will repel women a lot more strongly than it repels men. So if you want to increase the number of women, you need to cut back on the amount of geek culture in CS environments.
This seems to me to be obviously correct. But it seems that saying it makes a lot of people upset. Why? Are you afraid that you won't be allowed to be a geek? Do you look around you and get upset at the thought that someone might want you to clean up? What is it?
Let me go farther. I've noticed that many geeks don't want non-geeks around because they think non-geeks are less intelligent and would water down programming. Well certainly there are a lot of dumb people out there. But I've known lots of dumb geeks and smart non-geeks. In fact I'd guess that that geeks are smarter on average than non-geeks, but geeks make up only a small fraction of the really smart people out there. And furthermore I find the average smart non-geek more interesting than the average geek.
So from my perspective broadening the base of people in CS would be a good thing.