You are part of the royal family. Probably.

A leading geneticist has calculated that almost every Briton is directly descended from Edward III. But many find facts like this scarcely believable. Why are we so bad at probability?

When British actor Danny Dyer was told that he was descended from King Edward III on the BBC programme Who Do You Think You Are, this was his response:

“I need to get this in my nut […] My blood is his blood. I can’t compute this in my brain.”

Now, in his new show, Danny Dyer’s Right Royal Family, he immerses himself in the lives of his royal ancestors (with amusing results).

As it turns out, Dyer is not alone in his royal relations. Geneticist Adam Rutherford has worked out the probability of a British person born in the 1970s being directly descended from Edward. “Not being descended from him was 0.01 to the power of 27,” he found. So almost everyone is.

Edward III lived around 25 generations ago and had nine children. So think of their children, and then their children and so on, and it all makes sense.

Probability produces many amazing facts. How about this? There are more ways of arranging a pack of 52 cards than there are atoms in the universe. So every time you shuffle a pack, they will almost certainly end up in an order never seen before.

But many still instinctively doubt these statistics. One book, The Enigma of Reason, argues that when our ancestors lived as hunter-gatherers, clear reasoning had few advantages for them. But winning arguments helped to bolster their social standing.

Should we worry about our ineptitude at probability?

Do the maths

It is no big deal, say some. We were built this way for a reason. Our imperfect brains increase our sense of wonder at these unbelievable statistics. And our misconceptions can easily be overcome by education and rational thought.

This is an evolutionary oddity that we need to grow out of, reply others. Decision-making is largely about weighing up probabilities. In fact, we should all live our lives by maths, carefully working out the most likely outcome of all our actions.

You Decide

1. Do you really, deep down, believe that you are related to the Queen?

Activities

1. The mathematical explanation for the likelihood of two people sharing the same birthday has not been included in this article. Attempt to work it out.

Some People Say...

“Life is a school of probability.”

Walter Bagehot

What do you think?

Q & A

What do we know?
That, in many cases, seemingly unlikely statistics turn out to be true. We know, for example, that most people who lived in the Middle Ages, have millions of direct descendants from their children, their grandchildren and so on.
What do we not know?
Exactly why many people struggle to come to terms with these sorts of eye-popping statistics, and whether humans can ever overcome their doubts on these matters.

Word Watch

Danny Dyer
An actor known for his Cockney accent and generally hard-man roles, such as in Human Traffic and The Football Factory.
King Edward III
His reign of 50 years was the second longest in medieval England. Noted for his military success in France during the Hundred Years War and for restoring royal authority after the disastrous and unorthodox reign of his father, Edward II.
Who Do You Think You Are
A BBC documentary series in which celebrities trace their family trees.
Book
See the New Yorker article in Become An Expert for details.