>In humans, even a small loss in genetic variability such as cousin mating 1.5% is bad enough that we have laws against it in nearly every society.

I thought this sounded suspicious, so I looked it up, and it's not true. Cousin marriage is legal in all of Europe, Australia and New Zealand, South America, Canada, Mexico, the Middle East, Russia, and India.

In The USA, cousin marriage is allowed in 17 states. But 40 out of the 50 states allow cousin sexual relations and cohabitations.

The only places in the world that cousin marriage is illegal is in China, Korea, Japan and some states in the US.

Whatever you think of cousin mating, it's just not true that "we have laws against it in nearly every society." In fact, just the opposite, it is allowed in nearly every society.