Some ethnic groups do have different average levels of intelligence. Ashkenazi jews, for example:

http://en.wikipedia.org/wiki/Ashkenazi_Jewish_intelligence

My own guess is that for some blacks, there has not been enough time for the Flynn Effect to occur for them to catch up with the general population. This is not due to any fault in them, but a result of no/substandard education for many generations. I imagine in a few generations any difference from the average will disappear. http://en.wikipedia.org/wiki/Flynn_effect

Have you read it?

Am I wrong?

Well I read it because I wanted to know if it was really racist or not. Unfortunately that was 16 years ago, so I am not 100% sure of my conclusion anymore. But I think ultimately I didn't think it was racist. I seem to remember they explicitly wrote about the effect of environments.

Would have been curious to get an opinion by somebody who read it recently.

They seem to be saying that nature & nurture is at play. Your comment mentions only the first bit.