A lot of the posts here seem to be some version of "This just shows that women aren't cut out for CS." My experience makes me think this may be an American issue.
I have been working in electrical engineering for 16 years. (I know, not CS but chip design is a tech field with commonalities.) It is a majority male field with approximately 15%-20% women. However, NONE of them that I see were raised in America. Most of the women I work with completed undergraduate degrees in China or India and got a graduate degree in the US. There must be some reason why American women are repelled from engineering. Or is it that Chinese and Indian women are just fundamentally better at tech than American women? (Before anyone brings up the H1 visa issue, that's not what is going on here. We have a hard time finding qualified candidates regardless of where they are from.)
It would seem that the fact that we (in the US) socialize girls from a very early age to stay away from thins like tech is relevant here. If you are curious, go into any major toy store (e.g. Toys R US, the independent stores are actually a lot better about this.) There are vanishingly few toys that are just toys anymore. There are only "girls" and "boys" toys. The girls toys are all pink and predominately princess themed. Now, you may say that this just confirms that boys and girls are different but you would be using circular logic to justify a pre-concieved notion.
Children are very sensitive to societal norms, both boys and girls. When high school girls feel that being too smart will make them less feminine and threaten boys, they will have a tendency to conform to these expectations. Sure, there will be some who don't but they will be fighting the system to some degree.
Saying that the low percentage of women in CS is proof that women don't like or aren't good at CS is simply pointing to the current state of affairs as a justification that it is the only possible way things can be. The reality is more nuanced.