[MMM]

Yes, her son was born underweight.

The comparison of race with dogs is not misplaced in any way. Dog breeders want pure-bred dogs, but some of those breeds are essentially inbred and the DNA purity also essentially guarantees certain diseases or other negative traits will be continued generation to generation.

I think it is fair to make this comparison to humans, as we are no more or less complicated DNA-wise with canines, and although I have never heard of any negatives with racial "purity" in humans, but I suspect humans around the world are nearly as "racially pure" as they like to think.