We Are All Related! So Get Over It.

Hillary_Clinton_Donald_TrumpPolitics are saturating the U.S. news media once again as candidates vie for the presidential elections, still more than a year away. Every four years, news services “discover” that various candidates are related to one another. This week’s news is that Donald Trump and Hillary Clinton are 19th cousins. Their common ancestors include John of Gaunt, the duke of Lancaster, and third wife Katherine Swynford at the end of the 14th century — a century before Columbus sailed the ocean blue.

I have one reaction: “Ho hum, so what else is new?”

Of course, most every person in North America whose ancestors have been here for several generations is related to most everyone else in North America whose ancestors have been here for several generations. In fact, you and I are probably related, and we are also probably related to Barack Obama, Donald Trump, Justin Bieber, Celine Dion, and the local mailman.

Let’s have some fun with mathematics. Let’s assume that there is a new generation born every twenty-five years. Your two parents were born about 25 years before you were born, your four grandparents were born about 50 years before you were born, your eight great-grandparents were born about 75 years before you were born, your sixteen great-great-grandparents were born about 100 years before you were born, and so forth back into antiquity. In other words, the number of your ancestors doubles every 25 years as you go back in time.

If you take this back just 1,000 years, you’ll find that you have well over 500 billion ancestors in a single generation.

Obviously, that’s impossible as there are fewer than seven billion people on this planet. While mathematically correct, the practical reality is that you don’t have 500 billion distinct ancestors, but rather a much, much smaller number of ancestors who reappear over and over and over again in your family tree. The reality is that we are all the products of much interbreeding, and with that we have cousins… many cousins. Thousands of cousins… Yes, even millions of cousins. Every one of us has millions of cousins.

Proving all these relationships may be a challenge, but the relationships certainly do exist. You and I are undoubtedly related, and we are also both related to most every politician, Hollywood star, and professional athlete you have ever heard of. We are also related to less notable people, including the truck driver who delivered your furniture and the plumber who fixed the leaky faucet.

I mentioned earlier that most every person in North America whose ancestors have been here for several generations is related to most everyone else in North America whose ancestors have been here for several generations. However, the relationships go much further back in time and cover all areas outside of North America as well. We are related to everyone on every continent although we may have to go back many more generations to prove the connections.

By definition, cousins are two people who share a common ancestor. Joe Chang proved (see www.stat.yale.edu/~jtc5/papers/Ancestors.pdf) that the number of generations back to the most recent common ancestor in a randomly mating population is very closely approximated by the base two logarithm of the size of the population. So, for a population of a million people, it takes 20 generations to reach the most recent common ancestor — or about 500 years — because 2 to the 20th power is about a million. For a randomly mating population of a billion people, it takes 30 generations — 750 years — because 2 to the 30th power is a billion. In simpler terms, most of us can find a cousin relationship with most anyone else by tracing our family trees back an average of 750 years.

Of course, we are not all related only to “the good guys.” We don’t get to pick and choose our relatives. I suspect that you and I and Barack Obama and Donald Trump are all related to Adolph Hitler, Genghis Khan, Alexander the Great, Attila the Hun, Charles Manson, and Osama bin Laden. However, we undoubtedly will need to go back more than 750 years to find some of those connections.

We are all related. All these news stories are simply proving the point.

As Joseph T. Chang, Douglas L.T. Rohde, and Steve Olson observe in their 2004 paper on the subject of everyone being related to everyone else (Nature, Volume 431, Issue 7008, pp. 562-566), we’re all interrelated, and getting more so all the time:

“No matter the languages we speak or the color of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who labored to build the Great Pyramid of Khufu. [And] within two thousand years, it is likely that everyone on earth will be descended from most of us.”

The next time you read or watch a news story saying that two political candidates are related, turn the page or change the station. That’s not news.

28 Comments

That’s certainly right and yet the quest is still exciting. The discoveries are fun, regardless.

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    Statistically being related and proving a relationship are two different matters. Nearly everyone has ancestors who have no lineage records available which means the line ends. If all four of your grandparents have no records of their parents your lineage ends.

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You’re absolutely right, Dick. And perhaps even more thought provoking is that if you’re prepared to go back far enough to find a common ancestor, then we’re also related to anything that contains DNA – animals, plants, everything!

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And when you belong to some sub-group of the population, say Cherokee or Hudson Valley Dutch or French Canadian, the likelihood of cousins within those groups goes up. It is all very interesting and kind of funny.

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Then you have the odd relationships. Like my mother and I are cousins also. Back in early colonial times some of our family tree is more of a knot than a branch.

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Actually Hillary is probably related to every person in Quebec from her mothers side. Her 10th great grandfather is my 9th great grandfather. LOL!

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I am a descendant of Tristram COFFIN by 8 different lines, making my closest relationship to myself a fifth cousin, but also a number of tenth cousins.

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One of the fun things on Wikitree.com is the Relationship Finder. Wikitree now has over 10 million profiles and you can spend entire evenings checking out relationships to famous people. While Wikitree is working to become more international, it is still dominated by US profiles but with the Magna Charta Projects and European Aristocrats Project, Dutch Roots, German Roots, Czech Roots, more international profiles appear every day.

Charles (Maddox) Manson 19C3xR, George Washington 10C7xR, Kevin Bacon 11th Cousin.

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While everything you’re saying is true, in this case there’s no evidence. This was “found” on Geni.com. To guess that they are related 1000 times over would be far more true and supported by evidence than any specific claims made in that article.

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C. Christopher Sirr August 26, 2015 at 10:31 am

“The reality is that we are all the products of much interbreeding”. What becomes too much?
Obviously Hillary Clinton, who you mention, has had too much interbreeding.

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We are not ALL related. If you do not have Swedish or Finnish ancestors you could not be related to me. This is based on genealogy research back to the 1500s and ancestryDNA which shows me to have about 95% Swedish and 5% Finnish DNA. My Swedish ancestors (all 8 great grandparents and some great great grandparents) came to the USA between 1869 and 1886 from Sweden. They all (great grandparents, grandparents, and my parents in the US) married other Swedes. Your math doesn’t make sense. The 25 year generation is not at all accurate for my family. For instance, I was born in 1962. According to you my grandparents were born in 1912. Actually the years are 1888, 1893, 1895, and 1903. Off by a whole generation for one grandfather. My parents were 3rd cousins so that removes lots of ancestors there. I read somewhere that you should figure 30 years for a generation. That would be more accurate.

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    Nancy,
    How many markers were tested on your sample? Certainly not a billion. Even ignoring the fact that those test results are not always 100% accurate, they will only tell about the ancestors who contributed that specific genetic material. If you go back to the point where there are 500 billion pedigree slots there are lots of potential ancestors who might not have contributed any genes that have made it down to you but who would still connect you to others.

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    What if your Swedish and Finnish ancestors date back to the Vikings and beyond? As I understand history, some of the Vikings liked to travel to new territories for economic reasons (raids and/or trade). Therefore it is within the realm of possibility that the Norsemen had the opportunity to pass along their gene pool to local women in Europe, the Mediterranean area, North Africa, Asia Minor, the Artic and North America. Just think, your great great grandparents may have had relatives already living in America when they arrived in 1869!

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    Something to take into consideration, way back when, in Europe and Asia (including Scandinavian countries) it was very common for Royalty from one country to arrange marriages of their offspring to Royalty, Nobles or landed Gentry
    from another country. So as far as being pure blooded anything, in my opinion, there is a possibility that very little remains 100 percent pure.

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    East European history much earlier than the 1500s has the Scandinavian countries taking turns being in charge of Slavs down south, sometimes into Russia and parts of what’s now Poland. Nobody’s blood is as pure as we tend to want to think it is.

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I was bothered by the assumption of random mating, which is clearly not the case in human populations, and which leads to time estimates to a pair of common ancestors that is much too recent. I could not follow all of Chang’s math in his proofs, which gets very complicated, but he shares my concern: “An application [of the simple powers of 2 or n*log base 2] to the world population of humans would be an obvious misuse. For example, we would not claim that a common ancestor of every present-day human may be found within the last lg n generations. Even if we took n to be 5 billion, this would imply a CA just about 32 generations ago — perhaps 500 years or so. An important source of the inapplicability of the model to this situation is the obvious non-random nature of mating in the history of mankind. For example, parents are much more likely to live within a few miles of their children than a thousand miles away or halfway around the world. So the model studied here is too simple to be directly applicable to the evolution of mankind as a whole. In such complicated situations, the results sound a note of caution: if the logarithmic time to CA’s seems patently implausible, then at least one of the assumptions of the model, such as the random mating assumption, must be causing a great deal of trouble.”

This means that our common ancestors are a good deal more distant than the powers of 2 suggest.

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Does that mean that mean that my 19th cousin is a p o l i t i c i a n ? I’m emigrating.

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I once heard an archivist in New Brunswick (Canada) tell a group of researchers, “Remember that everyone in New Brunswick is related to everyone else, one way or another — Heck! We’re all so related that it’s a wonder by now we don’t all have just one eye in the middle of our foreheads or something.” Sure enough, my New Brunswick family tree has so many branches tied up in knots that it looks more like a big bowl of spaghetti than a tree.

Even if the mathematical model described in the “Nature” article may not work out for every single individual (especially among population groups that remained isolated from the rest of the world for a very long time), remember that researchers working with mitochondrial DNA (the kind that gets passed down to each of us through the maternal line) have concluded that the ancestry of every human living today traces back to a single female ancestor, whom they call the mitochondrial Eve, the mother of us all. So, we truly are *all* related.

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This article provides anecdotal evidence supporting
my theory that King Edward III (father of John of Gaunt) is disproportionately found as one’s most recent link to the British royal line. It would make sense; he had many children, and he was the last monarch before the War of the Roses which reshuffled the deck of the stratified English society.

I wonder if more reliable research has been done supporting this idea.

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Presumably then we can be statistically certain that a particular US presidential candidate IS the spawn of the devil?

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Assortative mating is a mating pattern and a form of sexual selection in which individuals with similar genotypes and/or phenotypes mate with one another more frequently than would be expected under a random mating pattern. Examples of similar phenotypes include, but are not limited to, body size, skin coloration/ pigmentation, and age.

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The good and the bad- all people of European descent are descendants of Charlemagne- and his stable boy.

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1-a tempest in a tea-cup. what a lot of quasi-glib and some rather witty observations. This should get the same ho hum one feels when a family researcher measures success only by the thousands of ancestors and relatives he/she has collected- usually without documentation. We could be using this awareness of universal relatedness to work toward a broader elimination of prejudice. How can anyone rant about another due to race or religion or politics or whatever, if we recognize how closely linked we ourselves are to those “others”.
2. I thought your comments section was screened for mean spirited, insulting or other crassly stupid negative hurtful remarks- you missed at least one (not counting mine which is not hurtful but could be called cranky).

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David Paul Davenport August 27, 2015 at 12:29 pm

Right you are, Dick. Now let’s all move on. Not a day passes at my local Family History Center when two or more patrons disrupt the research environment by talking loudly about who in their Ward they are related to. In my opinion they are wasting valuable research time, including mine, by not conducting research to locate “unsaved” ancestors and making it difficult for me to concentrate on resolving difficult genealogy questions. Frankly, one of the worst decisions Family Search ever made was to create Puzilla and this thing called Relative Finder. I would delete these in a heart beat if I could (and also deny access to the Temple for every church member who hasn’t indexed at least 100 names in the past week).

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