Can't see the family forest for the trees

Today I read a press release from Family Forest (a play on the term "family tree," I guess; the company sells genealogical resources) announcing "its discovery that presidential hopeful Senator Barack Obama's . . . mother, Ann Dunham, [has] a number of her ancestral pathways leading back to early colonial Virginia and New England." Obama's ancestors include his "12th great grandfather--the Hon. Laurence Washington, who built Sulgrave Manor in Northamptonshire, England. Over the course of five centuries, according to recorded history, he became the ancestor of President George Washington, General George S. Patton, Governor Adlai Stevenson, President Jimmy Carter, and Quincy Jones, Jr."

Wow.

Three years ago, Family Forest traced the family connections of George W. Bush and John Kerry, the two presidential candidates in 2004. According to that press release, Kerry and Bush are 16th cousins, three times removed. This means that the great (times 15) grandfather of one was the great (times 18) grandfather of the other. How far do we have to go to find this common ancestor? Probably to the early 1500s, probably somewhere in Europe.

This is amazing. I’ll bet not one person in a hundred today could tell you the name of one of his sixteen great-great-grandparents, and yet here are two families that can trace at least one of their lines back four centuries. (Actually, much further, as both Bush and Kerry can claim Marc Anthony as their 55th great-grandfather.)

Turns out that Bush and Kerry are related to a lot of people besides each other. The web site lists over sixty famous people, from Marilyn Monroe and Humphrey Bogart to Henry David Thoreau and Henry Wadsworth Longfellow, and their relationship to Kerry and Bush (usually both). Mormon leader Brigham Young was distantly related to Kerry (11th cousin 4 times removed), but more closely to Bush (5th cousin 6 times removed). On the other hand, Kerry is closer to Obama kinsman General George Patton (13th cousin once removed) than is Bush (17th cousin twice removed). Both are Charles Darwin's cousin: Kerry, 11th, 4 times removed; Bush, 14th, 5 times removed.

Between the two of them, they are related to 24 American presidents. They’re both related to 22; Bush is also distant cousin to another two. Abraham Lincoln was Kerry’s 20th cousin, Bush’s 7th (no longer bothering with the "removeds"); George Washington (another Obama kinsman) was Bush’s 11th cousin, Kerry’s 8th.

Some of these numbers, upon just a moment’s reflection, boggle the mind. Brooke Shields is Kerry’s 22st cousin, Bush’s 11th. Ernest Hemingway was Kerry’s 20th, Bush’s 22nd. Agatha Christie was Kerry’s 18th cousin, Bush’s 20th.

How many 20th cousins does a person have? The number varies, of course, depending on how many children your great (19 times) grandparents had, and how many children those children had, and so on. Let’s assume that each couple on the family tree had three children who grew up to have three of their own, etc. Historically, this is a conservative figure. In colonial times, the birth rate was double that or more. But let’s use three children per couple for our example.

With those numbers, one set of your grandparents will give you 6 first cousins. Your child will have 18 second cousins, then the next generation will have 54 third cousins, and so forth. By the time you get down to seventeenth cousins, the number would be 258 million, almost as many people as there are in the United States (just over 300 million.) Add three more generations, to twentieth cousins, and the number is nearly 7 billion, a little over the population of the whole planet today (6.6 billion).

Isn’t that amazing? We have more twentieth cousins than there are people in the world.

But there’s more. Those 7 billion are through just one set of common ancestors. You have two sets of first cousins, one through your mother’s parents and another through your father’s, and four sets of second cousins, and so on. Theoretically (it never works out this smoothly in real life), you would have over a million different sets of twentieth cousins, each set consisting of 7 billion people.

No wonder Bush and Kerry (and Obama) are related to so many people. I guess we all are.

But I still sorta doubt those press releases.

This posting originally appeared, in a slightly different form, in the Cartersville Daily Tribune News, Feb. 22, 2004.