What makes them dominant traits? You've got a chicken/egg problem.

It is natural that people do X... used to argue "it isn't wrong that people do X"-- sounds like a naturalistic fallacy to me.

By what standards does a mother decide (or specify) that a baby looks like her own?

Right. "Blacks" are not a race. They can be arbitrarily reclassified into any number of groups, and classifying races based on skin color is something which was formerly done.