To be fair, a pharoah only married one (half-)sibling. It wasn’t polygamous incest.
Sometimes it was. Ramses the Great was married to at least one of his sisters and at least three of his daughters.
Huh. The things I learn here! Thanks for this, I think…
Well then she has something in common with President Obama, who is a 9th cousin 6 times removed from George Washington!
eWWWWWWWW! Pass the brain leach, please!*
*This typo is worth leaving, I think. 
Weird I saw this tidbit this evening on E! News and they pushed the story with Ellen DeGeneres as her 14th cousin, and also mentioned George Washington. No mention of William being a cousin.
Ah…“news”…
No way - George Washington was a Kenyan?
And he wasn’t a true American since he wasn’t born on American soil. How much they have in common!
I agree, what if this rampant genetic mixing actually results in children who have more skills other than waving from cars? They may no longer be content to just sitting around in palaces waiting to bleed to death and actually try and interfere to the real world. <shudder>
Ah yes; the British original was Fewer than 14 Degrees of Separation, IIRC.
Obama’s mother was called Stanley? Not only was he born in Kenya, he was born to a man, baby! 
If you’re looking for a very crude estimate giving the portion (p) of Englishmen living in year Y who are not descended from Edward I, you can try a logistic function like:
p = A e[sup](1300 - Y)/G[/sup] / (1 + A esup/G[/sup] )
where A = 2,000,000 is the number of males when Edward starting having children in 1300 A.D., and G = 38 is a very crude estimate of years needed for growth of x2.72.
Plugging into this formula gives 99.9%, 98%, 79%, 22%, 2% for years 1585, 1700, 1800, 1900, 2000.
But the flaws in this crude formula would make a very long list! It ignores emigration/immigration, assumes random mating, ignores that Edward had several children, and G was a wild guess, just for starters. I vaguely recall once reading “almost every Englishman is descended from King John” which might be a plausible stab.
Probably didn’t have a long-form birth certificate, either. Hmmph. Poser!
This is really interesting, thank you.
So in my case, slightly under 3% of my ancestors are English, and by 1700 they had all left England and soon started marrying non-English. So that gives me (1-.98)*.0275 = only a miniscule likelihood of being descended from Edward I. Even so I know that Obama and I share an ethnically English ancestor from mid-18th-century Virginia. I 
pedigree collapse.
Two caveats:
(1) My crude formula was intended more as an example of the indicated math, rather than an authoritative formula for this specific question.
(2) Your calculation seems to assume a zero chance that a non-Englishman (or non-Brit?) descends from Edward I. But Edward had at least two daughters who married Continental noblemen, just for starts.
And…?
Every woman in Europe is probably his fourteenth cousin.
Don’t worry, I wasn’t taking that result as definitive. The whole point is that’s it’s interesting but ultimately not too meaningful to talk about descent from a common ancestor in the 14th century, whether you’re William or Kate or you or me.
Franklin Delano Roosevelt’s wife, Eleanor, was his fifth cousin, once removed. She was the niece of Theodore Roosevelt, who was FDR’s fifth cousin. They met at a White House reception in 1902, when T.R. was in office.
Heck, even I’m more closely related than that, and that line of my ancestors left Britain in the late 1600s.
Ha! I knew he was a no good rotten Hillbilly.
–sorry, HillWilliam. 