Btw I don't think the China thing is actually true unless genius means something like top 20%. I would imagine genius meaning something closer to top 1%.
The real interesting comparison lies elsewhere. Also we have to take into account that we can not use the same tests on intelligence on both populations.
I actually think that intelligence test questions have highly correlated difficulty when given to people from different cultures (even more different than US/China). I.e. there's broad agreement in terms of what questions are hard/easy.