You'll find if you take your family tree back far enough you are the consequence of such a relationship at some point. This explains why the world population is not well over 10 Billion as it would be if it was for inbreeding. It was common practise in the West in Ye Olde Days
....and it didn't do us in the West any harm, look at excellent public people like George Bush .... and me ... I'm totally sane
Look at America.... around 10% of the population goes back to about 2 pilgrim boats that landed, all full of families... with a good number bonking cousins.
Methinks CH4 are just making a story out of small numbers, as such inbreeding goes on in other animals daily and only a minority have genetic problems, however the stats of these problems is higher than if non-cousins bonked, but the numbers are still small in the overall scheme of things. In fact every human has a genetic flaw, most don't show themselves till you are older.... breast cancer susceptibility for one.
In normal pregnancy, only 5% of fertilised eggs make it to be a teenager.
