This topic actually facinates me and ive done a fair share of reading on the subject. Fast twitch vs slow twitch muscularity only captures a portion of the American definition of athletic ability (I say American, because if you were to ask a European, for example, who is more athletic, a soccer player or an American football player and you will get a very different answer than the typical response in this forum).
As for your assertion about geography and athletic ability, well, that's a very debatable and highly subjective take that has been disproven in many studies and not disproven in others (in other words, the evidence is inconclusive and the studies are often tainted). And there have been other studies that have shown the body can convert fast-twitch to slow-twitch fibers and vice versa through targeted training, which would suggest that there may be non-genetic factors at play in developing explosive power.
As for the Sicilian thing, it doesn't hold up that the genetic influence of African invaders/traders have somehow created athletes with fast-twitch dominant bidies. I suspect that this "thing" in recruiting that you refer to is at best ignorance and at worst, racist- based misinformation. The muslim invaders/conquerors of Sicily came from northern Africa (modern day Algeria, Libya and Tunisia). If there was truth to the theory, you would expect to see an abundance of explosive athletes from these countries (or Sicily for that matter), but this isn't the case, in fact, anecdotal evidence (Olympic summer games results) suggests it's the opposite.
Anyway, there's a lot more to unpack on this subject and I don't want to write anymore and I doubt anyone else has made it thus far. There's a lot of info on the subject out there if anyone cares to broaden their understanding of genetic, social and economic factors on athletic performance.
