[Doctor Stochastic]

If evolution and the "out of Africa" stuff were both true,then why didn't some parents in China,let's say,ever have a Negroid looking child?

Evolutionary theory says that they wouldn't. So you've answered your own question.

[nopardons]

Not really...evolutionary theory says that "throw backs" are always a possibility.And while there is some vague sense to why Northern whites' noses would have modified/slimmer nostrils,because of the cold,etc.,they have never managed to explain why some Asians,though not all,would have a different eye-fold,non-Caucasoid nostrils,even though they live in cold climes,etc.