Exactly. Couple that with a natural tendency to be muscular and powerful and correct training and you have a winning formula. Like it says early in the article, Rich kids can run well, but lack that extra Ommph.
Compare this to the African Middle distance guys, exactly like the above article, but they lack the muscular and power, and hence are light framed. You have literally thousands of people each year, trying out for a handful of top spots (cash and no more poverty are big motivators)
The good run well, those that have oomph run well, those that are slightly gifted and give it oomph succeed.
Us other nations really need to step it up Mentally. We need to be more Hungry for success, not to Race in finals or race beside Usain or Asafa, but to actually Win races and feel sick for not winning… For every loss, it just feeds you to try harder and harder.