I used to teach 3D drawing, the sort that uses paper, a pencil, and a ruler. The math was elementary-level. By the 3rd semester I taught this class, it got to where I could predict a student's future performance fairly accurately on the first day. Just by taking their race/sex into account.
The 'levels' of performance were:
1) White Boys (competent in 1, 2, & 3-point perspective)
2) White Girls (competent in 1 & 2-point perspective)
3) Black Boys (competent in 1-point perspective)
4) Black Girls (struggle even with 1-point perspective)
An exceptionally good or bad student might move up or down one level, and I even had a single student jump up 2 levels. But 90% of all my students ranked up in exactly this order. Clearly, this pointed out a difference in each race/sex's ability to handle abstract spacial relationships.
I should point out though that I cherished having black students. Because they were the ones most likely to ask questions and spark meaningful discussions during my lectures/demonstrations. Whenever I was cursed with an all-white class, they'd just sit and stare at me blankly. Taking in all I said without question, when what I wanted was for them to think critically about what I was presenting.
So Every race/sex has its better and worse qualities. We really need to be honest about these, and stop expecting identical outcomes from each. Instead, let’s work to enhance and benefit from everyone’s strengths, and stop beating each other up over (or ignoring) our weaknesses.