The best incentive I had to learn to fly was my mother trying to stop me!
Now I'm an instructor I'd say that less than 5% of our students are female, and I think the reason is simply this, that most females simply aren't interested in it. I doubt that proportion will ever increase.
A girl who is determined to be a pilot, or any other career for that matter, isn't going to be put off by peer pressure, lack of parental support or incompetent careers advisors. She will have the dedication, will and personality to succeed, and will just get on with it. This has been the case in aviation since Amy, Amelia, Beryl and co, and still is today, and I don't think it will ever change.
In that way we are no different to the boys with the same aspirations, there are just less of us.