That's a thread for another day, but if you ever get a chance, visit the Kenyan cities of Nairobi or Mombasa one day, get off the tourist path and check out the street action. You will be amazed. In Nairobi, where I grew up, I've seen and encountered untrained glue sniffing street kids, with fighting techniques and stunts that would shame many blackbelts of various styles. I've seen some of those kids challenge serious blackbelts in WTF sparring after only a few months of training. Turning those street kids into bonafide blackbelts is another story, though. But some of them acquire the discipline when they can find a good teacher, willing to teach them for free. One of those former street kids, who trained in the dojang where I began Taekwondo, is now Kenya's Taekwondo team national coach.
It's not just in the Third World where there are kids with amazing physical talent honed in the streets. Here in St. Louis, where I live, kids fly past my house in bicycles and skateboards and pull spectacular stunts that make me believe any good Taekwondo instructor could teach them how to break with a 540 spin kick in a very short time. But again, it might require an Herculean effort from even the best Taekwondoin to turn those kids into a Kukkiwon poom or dan holder.