I know I'll get banned and cursed for years for that but here you go:
Oh stop it, those are gender differences and girls also enjoy their differences, even if they're unfortunately imprinted by culture. They're untouchable, they are given what they ask (which is: often dolls), they're social. And the few that are in IT, they don't show up at the Java User Group, even if it's their job, even if it's free, even if it's at the same time as for boys.
They do show up more often at higher-class networking parties where they may make connections with product managers and be promoted, rather than stay programmers like us for a bit longer.
Of course there will be counter-examples, but I see girls in IT getting promoted MUCH faster than boys. In my 14-people office? 4 women-project-managers, 1 woman-architect (who doesn't know GIT), 1 female programmer (with 2 years of experience) and 8 male programmers. Yes, I'm making this observation about my team to imply that women have better jobs, sooner than boys, and it does imply that males don't get promoted as easily as women, at least in the world around me, and I'm saying an IT career is an excellent path for a girl.
Before anyone says "Women get promoted quicker because they're just better at their job", I'd note they turn over this exact argument when it's directed to boys, by suggesting they didn't get the education, incentive, support or opportunity. It's not about anyone being better. It's about how we reach fairness.
I do see that some of the world is different for girls, but unfairness is reported more often than advantages.
Edit: "Why are there less girls at the JUG, is it because they're uncomfortable with 95% men?" > Or that they aren't involved much and reserve their evening time for their social life. The only way to be sure would be to ask them, and they'll probably remark they'll be promoted whether or not they attend the JUG, if you've followed the story of my team.