Indeed. I know more more women that are mathematicians than men, and I know a few. What I have observed though is that more women give up early when things get mentally tough and require deep, exact thinking. Those that push through are not better or worse, so this seems to have nothing to do with talent or aptitude at all. I have heard (western) women women justifying their giving up because this was too much effort and they would marry or find a man to do this for them anyways. I also have taught a group of female honors-students from Tunesia that claimed "mathematics is easy". (Well, this was 20 years ago, but they knew their options were pretty limited if they did not achieve economic independence.)
I strongly suspect this is indeed a cultural problem and western women more often think that they do not need to bother. Of course, all that modern "feminist" BS about mathematics being "male" does not help at all.