On my travells through China I have noticed that Chinese people have a remarkable ability to squat. Why is this? I'm born Chinese yet can't squat like they do.
Squatting like any other activity is one that increases with practice, since they have been doing it for decades and use toilets in a similar manner they have become very adept at squatting. In fact if you watch the film Coliseum / Way of the Dragon by Bruce Lee (where Bruce kills Chuck Norris) near the start when he gets off the plane and into a cafe (where he orders 10 bowls of soup) even Bruce Lee squat on the sit down toilet. I can't squat flat footed and have to hold on to something.
But really as said it is to do with cleanliness I think anyway, as when you squat on a toilet or squat instead of sit on the ground nothing bar the bottom of your shoes touches the ground. Added to the fact that the CCP doesn't exactly build many benches people squat around places when waiting.