You're assuming that intelligence is the determining factor in winning a Nobel prize, which seems spurious at best. Work ethic and training, particularly early in life seem, to me, like they'd be better predictors. I'd posit that Jewish culture is better at nurturing intelligence before I'd conclude that there's some ethnic superiority going on.
While there isn't a bullet-proof case, there is quite a bit of evidence for an ethnicity-intelligence correlation.
The only value judgement I was making is that higher intelligence is superior to lower intelligence and that Nobel prizes is an extremely poor proxy for intelligence.
But don't most Kenyan and Ethiopian marathon winners also grow up in Kenya or Ethiopia? I.e. how do we discount at very least environmental factors (including, for instance, diet), even if you doubt cultural ones?
No. There is a hugely disproportionate number of Americans and British of Somali, Kenyan, and Ethiopian origin who excel in world class distance running (Adbirahman, Farah, and many more, including a big new wave of Somali American after).
Fwiw I don't think you're necessarily wrong about intelligence but from what I remember The Gene (Siddhartha Mukherjee) does have a few passages contradicting this theory. Also by questioning the validity of IQ tests.
Could it also not be that jews are just more motivated to get in to STEM fields and perform well, for cultural reasons or otherwise?
Similarly, Malcolm Gladwell mentions a theory about why "Asians are smarter" which according to him may be related to hard and smart work leading to bigger rice harvests, and other factors (see here https://www.cs.unh.edu/~sbhatia/outliers/outliers.pdf).
While I have zero interest in the cultural implications and all the moral panics surrounding these issues, I don't think intelligence being mostly down to genetics is a proven fact. I find it gets extremely complicated very quickly.
Genes are hugely influenced by their environmental (cultural) triggers and those should not be ignored.
Some people would say that this is cultural. I doubt it -- I think it's genetic. Intelligence is a physical attribute determined by genes, just like every other physical attribute. It's really no different from the observation that Kenyans and Ethiopians win most marathons.
In general, we should expect different traits to be exhibited at different frequencies by different populations that were reproductively isolated in the past. This doesn't mean prejudice is okay. Not all Jews are smart, and not all Kenyans are going to win marathons. We can acknowledge these correlations without behaving in a prejudiced way toward individuals.
Most people would rather not talk about this. And that's certainly my rule of thumb for in-person conversations. But, hey, we're on the internet.