On the subject of the most controversial aspect of IQ, the IQ differences between different ethnic groups.

It seems that the current most widely accepted explanation to the IQ differences between groups is that of nurture. That is the position Wikipedia for example holds and specifically asserts that it isn't genetics. https://en.wikipedia.org/wiki/Intelligence_quotient#Race

However, so far I have not seen one study that proves this by producing results where different ethnic groups have similar IQ scores when the nurture is the same with both groups.
Have I missed such studies? Or is this quite strong and widespread assertion based on just theory and reasoning (both subject to biases) or is there actual hard scientific evidence of this being the case? Am I missing something else here?