There is a lot of debate going on about Title IX, the federal law that requires gender equity in sports. I just want to weigh in on one point: girls' interest in sport.
If I had a daughter, I wouldn't want anyone telling her that boys are more interested in sports than girls or assuming that she is less interested. That would be no different than believing stereotypes such as boys are more interested in math or blacks are more interested in basketball than tennis. Sports participation is as important for our daughters as it is for our sons.
Boys have never had to prove that they were interested in sports to get the opportunity to play. Why should girls have to "prove" their interest? Society just encourages and expects boys to play. Interest is a function of the opportunity to play and encouragement to take advantage of that opportunity.
Boys are not born with a "sports interest" gene. They are pushed, cajoled, expected and sometimes even embarrassed into playing, and we provide them with every opportunity to do so. A coach who sees a big boy in school makes him come out for football. Tall boys are dragged onto the basketball team. Boys who run fast are encouraged to run track.