[Rifleman]

Inbreeding is no bad thing, as long as you start with good stock and cull the worst third of the offspring. The problem is that, the Saudi Royals for example, failed to do either.

[FITZ]

But breeding humans --- how are you going to cull? It's easier with animals --- you just neuter or spay the less than perfect when you're inbreeding --- but even with that inbred animals are not the best, even if they have some traits you wanted, they're usually mentally not the best.

A one time breeding of cousins isn't so much the problem because it bring together the same genes for one generation --- but when it's done for generation after generation, after a while all the genes are the same.