I wonder how much role models actually play a role. I got into programming because I loved programming, it was something I could do at home with minimal ramp up time or gear.
There is a lack of role models because there is a perception among the younger generation of women that programming is not a creative endeavor, which makes a lot of women away from learning programming. The society's portrayal of programmers as geeks or beta males does not help either. People are the sum total of the 5-10 people they closely associate with, and most girls do not find their friends wanting to be programmers when they grow up. Peer support, role models, are key. When women like Sheryl Sandberg of Facebook start showing up on TV and the idea of successful women in technology is portrayed to be appealing, you will slowly find women taking more to technology jobs.
Programming is also a solitary endeavor so close to impossible that it seems to require obsession just to reach a minimal level of competence. If anyone is dependent on peer validation and role models (which basically didn't exist for any of us until the first dotcom bubble in the mid-90s), if they care more about what other people think than the Platonic ideals of computation, I don't think they're equipped to thrive and do noteworthy work. Even if we did have some way to make a kid more asocial and hyperfocused while growing up, we'd have to think hard about whether it's ethical to do it to them in this extrovert-oriented society.
Honestly, there's no easy way to tell if programming is solitary because it has to be or because the culture that grew up around it prefers it to be. Consider pair-programming for a counter-example.
