TLDR; The 10,000 hr practice myth has long been busted by series of studies and this meta study is another one in the series focusing on sport. It turns out th

TLDR; The 10,000 hr practice myth has long been busted by series of studies and this meta study is another one in the series focusing on sport. It turns out that among non-elites, only 18% of performance difference can be attributed to deliberate practice! More surprisingly, there are significant non-elites who spend same or more hours in deliberate practice which means that simply looking at this number doesn't allow you to accurately distinguish between elites and non-elites. Finally, starting at childhood has minimal advantage in performance difference. This is another big stab in the nature vs nurture debate. There are many studies (also cited in this paper) which has indicated that deliberate practice only account for 30% of performance difference in activities like chess requiring purely cognitive abilities. So for physical activities, it makes even less difference! The paper has extensive references at the end which indicates that rest of the majority of differences comes from genetics and possibly psychological factors such as confidence, sensitivity to rewards, ability to focus, performance anxiety and so on. So currently, it looks to me nurture contributes 1/3 and potentially (this is not in paper) nature another 1/3 and psychological factors another 1/3.