For very bad reasons (to please my father), I was a math major/ chemistry major up through my first year in college. This was taking place in the 70's, so it meant that I was either the only female or one of the few females in my math/science classes. This wound up making these classes far more unpleasant than they needed to be. The fact that I wasn't supposed to be there meant that everyone acted like I was invisible -- not pleasant. The fact that these classes were 99% men, contributed to a fairly cold and extremely competitive atmosphere, which made these classes more unpleasant than they had to be. I am a fairly bright person and it wasn't the material that put me off so much as the presentation (truth writ in stone) and the atmosphere that put me off. Now someone could be looking at the situation and say, you see, that proves that women are innately less able to deal with math/science then men, but my experience was completely different from that.
It also seemed very strange to me, sitting in those classes, that an "individual achievement" model was imposed to such a degree, when science is something that is really best and most effectively practiced in groups. But no effort was made to do this at all.
Joanna