Ok, I can get you can somehow socialize a person to pretend be dumber than they are, but how do you socialize someone away from being dumb? And why does that not work for boys?
I think poor achool performance is more a function of behavioral issues than "being dumb" -- not because everyone is smart, but because the bar in your average American school is more about following directions than anything else. Boys lagging behind girls in social development is well-documented, right?
And at the Fields medal level it's less about "pretend you're not smart" and more about "we just don't think it's a good idea for you to skip grades".