As I already mentioned, the warrior gene is the most famous, but gene expressions thought to be related to intelligence have been found to be expressed far more often in Eurasian populations than in South African.
Also what Watson said. Some people use some nebulous pilpul where they say that because we haven't deduced the EXACT cause you an't make any claim at all which is total bullshit and these people will continue to do so no matter how much evidence you find, once all the genes are found they'll move on to some other niggling detail. Science is observation. Usually when a study finds something it's noted in probability not fact because science isn't dogmatic and random distributions are random and there's always a chance the data just fell at a curve.
I mean a good comparison is smoking and lung cancer. There is NO "proof" that smoking causes lung cancer. Crazy right? It's a well known fact that it does. But you can google it if you want, there is no scientific consensus on how exactly smoking tobacco = lung cancer.
What there IS however, is plenty of EVIDENCE that it does. An overwhelming amount. An undeniable amount. People who smoke have it at a rate so much statistically higher that the possibility of no correlation is approximately zero.
It's the same for racial characteristics. The evidence is overwhelming from simple observation, IQ tests, the mirror test, behavioural differences both at home and abroad, both within and without their culture, adoption studies, etc.
But then you get niggling fantasists who claim that because you haven't diagnosed the EXACT mechanism behind it therefore it could be anything. That's not exactly wrong, in the same way because we haven't diagnosed the EXACT mechanism behind smoking causing lung cancer it COULD be anything. We cannot make an ABSOLUTE claim without the evidence. But as with the cancer example, we CAN claim that the evidence OVERWHELMINGLY suggests in favour of one school of thought.