[dumbo-octopus]

It is indefensible to make arguments of likelihoods without and understanding of context and priors. If I listed 1,000 people from around the world at random and claimed we all had a shared great^N grandfather (with N not so large at to be trivially true), I’d need some rather significant proof to back up at that claim, and barring that we could say it was unlikely to be true.

If on the other hand I consulted my family’s genealogical records that had been painstakingly maintained for generations, including only those matrilineal lines that are most solid to trace, and from that listed 1,000 folks who have the same grandfather, then my claim would not be very unlikely at all.

This case is much closer to the latter than the former.

[netdevnet]

Given the socio-historical relevance of family trees, genealogical records of anyone but the wealthiest are likely unreliable the farther you go back