Progressives like to think of all people as blank slates which can be elevated to equality with sufficient resources. If people were not blank slates, if our biology imposes limitations on us, then that carries two implications: First is that there are limits has to how many people can be elevated to equity. Second is that the unequal status quo may actually have good reasons to operate the way it does, given the constraints of human nature. Both of these problems place limits on the progressive ideal of universal equity and add legitimacy to the present, unequal society. Naturally, this is unacceptable to progressives.

Progressives believe that it is possible--and morally necessary--to socially and politically engineer away the ills of society: racism, poverty, pollution, etc. But if people are not blank slates, if human nature is a constraint, then that puts limits on how effective those engineering programs can be. Worse, it also suggests that the institutions that progressives decry as oppressive and illegitimate have good reasons to exist the way they do. And once you start noticing that, it's just a matter of time before you're carving swastikas into your forehead.