My own biases as well as basic knowledge of the respective cultures makes me fairly certain that it's culture in both cases rather than genetics, though.
This is true, which is why we can only say something useful about averages between populations, but not extrapolate to particular individuals.
> there has been no discovered correlation between certain genetic traits and success
This is very false. IQ is largely genetic, and the biggest predictor of life success of any kind, especially in relatively well developed societies.
If I ever get really rich, that is what I plan to do. But the Flynn Effect has started to slow down or stop in many countries, indicating that we've plucked all the low-hanging fruits and we're running out of obvious ways to do that.
We'll probably fall down slightly in terms of average IQs in the population before IVF and genetic selection allows us redress the problem. Don't mention the E word (eugenics) though - germinal choice is a better euphemism.