This is actually an interesting thing! Because it turns out this young lady is RIGHT.
But that doesn’t mean what it seems to.
King John died in 1218—800 years ago. If you figure that on average, humans tend to reproduce at roughly the age of 20 (honestly, given the weight of history the age would probably be skewed younger, but 20 is a nice round number and it errs on the side of caution) then you can figure roughly 40 generations of humans between 1218 and now (20/800=40).
Now there’s a simple geometric progression to the total number of ancestors you have from any given generation. 1 of you. 2 parents. 4 grandparents. 8 great-grandparents. 16 gg-grandparents. 32 ggg-grandparents, etc. Which means there’s an equation for that! It goes like this:
(the number of ancestors of a given generation) = (the number you start with) * (the multiplier, magnified to the power of the generation in question – 1)
So! We can find the number of ancestors we have from 40 generations prior to us by starting with 1 (that’s you or me or Obama) * 2 (that’s the multiplier—each previous generation is twice as big as the younger one before it) to the power of 40-1 (that 1 is because we’re looking at 39 generations before us. We’re generation #40).
Okay, let’s set this loose!
ancestors = 1(2 to the 39th power)
And the total is…549,755,813,888!*
(In fact, people who are professionals at this estimate another couple of generations in there, giving us twice this number, or even more.)
NOW. How many people do you think LIVED in Great Britain in 1218?
There was a population boom in the 11th century, so the population of Europe was doing pretty well. Historians estimate a rough peak of 120 million people in Europe—that’s all of Europe!—around 1250.
But you have more ancestors in that generation than there are people in the entire continent! What can that MEAN?
It means that chances are, you can trace the path of your ancestry back to EVERY SINGLE LIVING PERSON on the continent of Europe at the time of King John’s short-lived reign—and most of them you’re related to along multiple vectors. And furthermore, chances are you’re also related to everybody who was alive in Asia, the Middle East and Africa at that time, because by the 1200s, there was plenty of intercontinental trade (and conjugal relations) along the Silk Road and through Northern Africa.
So this young woman was quite correct. But in fact the VAST MAJORITY of us are related to King John. What’s really weird, actually, is that there’s a US President who ISN’T related to King John. That’s pretty frigging bizarre.
It’s not a conspiracy. It’s just statistical odds.
12-Year-Old Discovers All U.S. Presidents Are Direct Descendents Of King John Of England – The…