9th Circuit Court of Appeals: Still looney after all these years

[lucrezaborgia]

(02-10-2012 12:18 PM)JLL Wrote:  As for cousins marrying, I don't know. Hopefully we learned something from the Habsburgs! All that intermarrying didn't work out too well for them.

The problem wasn't mainly cousins marrying with the Hapsburg family and BTW, it was only the Spanish branch that had this issue.



The issue here is uncles marrying their nieces...which is wayyyy closer than cousins! First cousins only marrying first cousins over and over leads does lead to a much smaller gene-pool tho which only exacerbated things when uncles married nieces.

http://blogs.discovermagazine.com/gnxp/2...hapsburgs/

Quote:What are you doing here is summing up through all of the distinct paths to common ancestors. You weight this by the number of individuals between the common ancestor and the individual whose inbreeding coefficient you are calculating (note that, for example, some of Charles’ lines up ancestry back up to his common ancestors have different numbers of generations). Finally you have to include in the inbreeding coefficient of that common ancestor.

Let’s play this out for a brother-sister mating. Assuming that the grandparents, of whom there are only two, are unrelated. So FA = 0. Then, it simplifies to:

FI = (0.5)3 X ( 1 ) + (0.5)3 X ( 1 ) = 0.25

In other words, Charles II was moderately more inbred than the average among the offspring from brother-sister matings!