Correlation and causation are a very different thing.

I don't have a solid enough understanding of the research to say whether IQ scores are correlated with race, but it seems plausible enough to me. That is very different from saying races causes it though. To study such a thing you have to control for so many other environmental and economic factors that it's unrealistic to do. The population sizes would be too small, or you missed controls and the data is garbage.