Inequalities of social goods between gender, racial, or other groups call out for explanation. Such inequalities might be explained by socialization and discrimination. But historically some have attributed these inequalities to biological differences between social groups. Such explanations are highly controversial: on the one hand, they have a very troubling racist and sexist history, but on the other hand, they are empirical claims, and so it seems inappropriate to rule them out a priori. I propose that the appropriate epistemic attitude toward biological explanations of social inequalities is a general but defeasible skepticism. I then turn to the appropriate moral attitude, arguing that when such explanations are inadequately supported, they are offensive.