themade.org teaches free programming classes to kids. We've been doing this for 2 years now, and most of the time, our ratios are 50/50. Yesterday, in fact, we had 3 boys and 6 girls for our scratch class, then had 8 girls and 2 boys for our interactive fiction class, taught in Twine.

Couple things we've learned. First, girls default to pair programming. They cluster, they work together, when they have a problem, they solve it for one another before asking the teachers. They work together and don't compete. The boys compete and try to get way far ahead of the teachers, and end up getting lost. The girls all move at the same pace except for the ones who were advanced-class level when they showed up.

Second thing: little girls are not affraid, and not any less able to do this. It's a societal thing that pushes them away. They see the girls in their classes interested in other things, so they don't get interested in computers. Instead, they get interested in facebook, not the computer itself, because their older siblings use it, their friends use it, and they then learn that computers are for socializing. Given the proper environment, they can learn anything a geek would learn, it's just that they don't get spoon fed computer knowledge, they get spoon fed facebook, Snapchat, Pokemon and Minecraft knowledge.

Third: Minecraft cuts across all genders. All kids absolutely adore Minecraft, and about 50% want to learn programming just to make mods for the game.

Finally, girls who come to our classes keep coming back. They have a little social group with the other girls, and they welcome in other girls. The boys are left out, mostly, but that's fine as they're not having trouble learning or keeping up. The girls in our classes are their own support mechanism, and they tend to become friends outside of classes.

So, learn from this what you will.