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Old 09-25-2012, 11:26 AM
septimus septimus is offline
Join Date: Dec 2009
Location: The Land of Smiles
Posts: 15,483
Originally Posted by Blake View Post

I can't make sense of this.
Several examples have been posted. Here's one from Real Life!

My present neighbors include two brothers from another province who came here and married unrelated women. One of the wives has a brother married to the other wife's sister. All three of these couples had children. (In fact, I've been to weddings for four of the children from these marriages.) All of these children are either siblings or first cousins with each other, yet share no known common ancestor. (Those connections don't involve us, but my wife has relatives who are cousins both on her mother's side and on her father's side. And, no, none of this involve inbreeding -- in all this genealogy I can't think of a single instance of known relatives marrying.)

To answer OP's question (but with the numbers 12th, 20th, 30th, just wild, probably conservative, estimates):
* I guess that a typical American is 12th cousins (or closer) with most other typical Americans.
* That same American is 20th cousins with 99% of living humans, and 30th cousins with 99.99%.
Getting that 99.99% up to 100% may be fraught with uncertainty, due to outliers like the Sentinelese.