Please read up on the origin of IQ tests. To the extent they are calibrated to anything apart from other IQ tests, they are calibrated against academic performance. Because they were developed originally by British and French scientists, they are calibrated against specifically European standards of academic performance.
There is no objective, unambiguously defined, quantifiable quality of "intelligence" that IQ tests can be said to measure. It is an entirely subjective test with no real scientific basis. In fact the only thing that IQ tests absolutely and definitely measure is the ability to do IQ tests.
Because IQ tests are calibrated mostly against a cultural artifact (European academic culture) Cultural bias is as likely a reason for variations across different cultures (very closely correlated with different races for obvious reasons) as any other factor.
Until you can rule out cultural bias in any IQ test (and I really don't see how you can) all your theories about genetic differences are meaningless.
For extra bonus points, find me ANY objective, unambiguous and measurable definition of the term, "intelligence."