I agree (and I see sex/gender as far more valid of a biological concept than "race", for the record), but I've noticed a correlation between people who would describe themselves in terms like "race realist" and people who think there's good evidence for women being "less suited" to math and science than men, cognitively speaking. (And again, getting deeply into this right now is not something I'm going to do, it would be wandering off-topic for one thing.)