Consider these two statements: 1) The female sex is intrinsically(biologically) uninterested in Computer Science. 2) Girl's are raised in an environment that pushes their interest away from Computer Science.
In each statement, girls are not interested in Computer Science. But the first statement carries a tremendous amount of baggage with it, and comments on significantly more than cultural interest. It is, to put it lightly, a fantastic claim. And fantastic claims require fantastic evidence.
I don't think anyone is afraid of admitting that girls have been less interested in pursuing Computer Science than men. That's not really at issue. What's at issue is the cause and context guiding the group's interest.