In the previous post referring to a study showing ethnic differences in 5 year old, I stated my belief that the differences weren't innate. Something in the study reaffirms that belief, but I'll just provide a bit of context before I explain what it is.
One of the strongest argument that racial differences in intelligence are down to genetic factors rather than cultural factors has been the long standing IQ gap between blacks and whites that has been observed in the United States since mass testing was first undertaken by the US Army during World War One. The difference then and now is about one standard deviation or 15 points.
However if this is a consequence of genetic differences in IQ, then blacks and whites in the UK ought to show a similar gap. However the results of what appears to be an IQ type test from the Millenium Cohort Study are:
Black Caribbean: 98
Black African 91.4
In other words White children score 11 points higher than Black African children and just 4 points ahead of Black Caribbean children. The difference in both cases is much smaller than the US differences.