Men comprise 90% of heads of state, 90% of Fortune 500 CEOs, and 90% of applications for patents. Prestigious positions are dominated by men.

Why is this? Motherhood, discrimination, social networks and patriarchal institutions all play a role. But there may also be gender differences in personality. Men are typically more confident and competitive.

Is equality then doomed? Should women be urged to lean in? And how much do gender differences in personalities really matter?