So we have those who attack "subjectivists" for the idea that all sex differences are socially constructed (as part of a larger attack on archaeologies of truth) . Well, difference between beings is not socially constructed - there are differences between every single being - but sorting based on those differences is certainly socially constructed. Sex difference is socially constructed not because difference is socially constructed but because the systems of differentiation are socially constructed. And so it is with any system of differentiation.