You're right, nothing is stopping them from learning it, and nothing is stopping them from being better.
But it's not a secret you have to work harder at things you're not naturally good at. Upbringing is an ideal area to argue about because it has the potential to destroy any argument in it's tracks.
"well, if they raised her on nothing but composition, she'd be a great composer!"
this is true, but it is also true that maybe she won't. Maybe she'll hate the field and be sloppy at it. Upbringing plays an important role but doesn't give any kind of real value.
Why is it that 90+% of students in the math oriented fields are men? Why is it that a HUGE majority of builders/carpenters/architects are men?
Why is it that there is a very large spiral of increases of women doctors?
Mayhap it's upbringing, but do any of you deny that there are traits in women/men that would have brought them closer to that profession?
If you can't seem to grab math related concepts as quickly as others around you, are you going to compete with them in that field? What if you had something they couldn't do? Still going to go on with the math route?
Face it, you take what you can do naturally, excel, and then dominate with it.