Mathematical ability is most remarked on at the far right of the bell curve. It is very possible (and there's lots of evidence to support the argument) that women simply have lower variance in mathematical ability. The average is the same. Whether or not 'lower variance' implies 'inherently weaker' is another argument, but it's a silly one.
I'm much too lazy to cite the data, but a quick Duck Duck Go search or maybe Google Scholar search could probably find it. An overview with good references is here.
Is mathematical ability a bell curve?
My own anecdotal experience has been that women are rare in elite math environments, but don't perform worse than the men. That would be consistent with a fat-tailed rather than normal distribution, and also with higher computed variance among women.
Also anecdotal, but it seems that when people come from an education system that privileges math (like Europe or Asia as opposed to the US) the proportion of women who pursue math is higher. In other words, when you can get as much social status by being a poly sci major...
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