Take the Kenyan (or more generally Central/Eastern African) success at long-distance running. This is certainly not in dispute: they've dominated the sport for quite some time now. But the reasons behind this are very poorly-understood. Here is a review from 2000 that presents an (admittedly out-of-date) review of the research, for example:
https://bjsm.bmj.com/content/34/5/391
In particular, the following passage is worth noting:
"However, irrespective of the existence or otherwise of any physiological advantage, it is possible that the attribution of caucasian running “failures” to anecdotal stable external factors disempowers caucasians. Similarly, this attribution style empowers the East African, just as it did the Scandinavians in the early 20th century and Australasians in the 1950s and 1960s, with a psychological advantage, the importance of which cannot be overestimated."
Or, in short, it is worth asking, "Are this stereotypes self-fulfilling prophecies?" Especially in sports, there's a great deal of importance that can be attached to, say, funding, or facilities, or inspiration: the choice of which sport a budding athlete pursues is not arbitrary, and owes a lot to the opportunities available to them. You don't see many Kenyans competing at the top level in track cycling, but then again, how many velodromes are there in Kenya? None, apparently, so of course no-one enters that sport.
Success begets success, anyway, is the point. It becomes difficult to prove that African long-distance runners are just going to be naturally good at that for factors outside their control, when you have to disentangle various social and cultural factors.
I could go on. But it's just common sense not to make the statement that "Central/Eastern Africans are good long-distance runners" without adding a tonne of massive caveats and small print.