I'd argue there is some truth to both. However I don't think that they are the primary reasons for the differences we see. In general men are more likely to have a sort of borderline autistic mindset in my experience. We do things that most women would probably find utterly pointless, like video games all day. Some women are obviously like that, just an awful lot less in my experience. In my opinion that isn't just a social expectation, I think men and women are wired differently.

As for race, I'd argue the main reason black people are over represented is because of genetics. Higher muscle to fat ratio, more fast twitch fibres and in the case of East Africans it seems pretty obvious they have some extra capacity to run further at quicker speeds.

No doubt there are those reasons of culture, but I'd argue they excel for reasons beyond simply the fact they played basketball as a kid.