One of the most interesting things I've read (or listened to) about expertise is a podcast interview with the author of
The Sports Gene[0].
> So in my second chapter I sort of tell a story I call the 'Tale of Two High Jumpers,' in which I sort of profile two high jumpers, one named Stefan Holm, who over the course of 20 years--and by his estimate, 20,000 hours--made incremental progress every year, to the point where he became one of the best high jumpers in the world. And then in 2007 he travels to the World Championships, and is met by a total unknown, a Bahamian jumper by the name of Donald Thomas, who just recently had started high jumping, basically because he had found out he was good at it on a lunchtime bet at his college. And so, Donald Thomas is closer to 0 hours, and Stefan Holm is closer to 20,000 hours. So they average 10,000 hours. But Donald Thomas actually wins that competition. And so I thought it was a good story to explain the fact that not only is there huge variation, but different athletes can get to the same place with both different biology and different training programs.
[0] http://www.econtalk.org/archives/2013/09/david_epstein_o.htm...