Societal expectations do play a big role, and it's an open questioned as to whether that's a Natural Rule or whether we just haven't tried other cultural config

Societal expectations do play a big role, and it's an open questioned as to whether that's a Natural Rule or whether we just haven't tried other cultural configurations enough yet. And you're right, psychological gender probably does play a large role in the effects. It's helpful to note here that biological gender, psychological gender, and gender expression do not vary independently though.