Question

It is said at 6 degrees of separation everyone is connected to each other, how dispersed is a 5th cousin?

Comments

5th cousin is about the average degree of relationship between random human beings.

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Ben: I doubt that's true. You're telling me that I'm related to an Inuit within the last 6 generations? Or an Australian aboriginal? Naah.

35 generations, maybe

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It's not that you're a 5th cousin to everyone, but that the mean genetic relatedness of human beings is approximately equivalent to 5th cousins. That's why autosomal genetic tests of relatedness don't work much beyond about that degree. The signal to noise ratio is close to 1 at that point.

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Not being able to discern between a 5th cousin and a random person by testing isn't the same as being related to that degree.

The "mean genetic relatedness" is the subject of many learned papers, and I can't find one which states it as simply as you seem to imply, they're full of integral maths and never seem to reach a firm conclusion.

Using yDNA and/or mtDNA tests and triangulation, we can prove firm relationships at a much farther degree than this.

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Oh no, not integral maths!

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Than-you everyone for sharing your viewpoints, they have all helped my understanding of the perspectives of relatedness, much appreciated.

Answer 1

6 degrees of separation is not necessarily DNA related. A 'separation' is a connection/relationship that may not be genetic, ie, a workmate, friend etc.

A fifth cousin is when you have a gr gr gr gr gr gr grandparent/s in common so that would be 7 degrees up to your grandparents and another 7 down to the fifth cousin (Hope I did that right..lol) but the 'theory' is that you would have a closer connection through a non-genetic relationship, ie, your sister-in-law's father works with someone's son....five separations.

Comments

A closer (smaller) number, but it's not genetic.In fact as far as genealogy is concerned, it's  meaningless.

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The theory of 'six degrees of separation' was never a genealogical term.  Not 'meaningless' with regard to how the question was phrased.  I am not sure how your answer is contributing to the conversation?  I am confident that my answer responded appropriately.

Have a nice day.

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Kylie, I think you may have read Tom wrong.  I don't think he was contradicting you, in fact I think he was agreeing with you, just saying it differently.

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Exactly--the "six degrees of separation" theory is about social and professional connections, not genetics. Jenny Hoffman (living, no point in linking) has no blood connection to me within 30 generations according to the relationship finder here on Wikitree--she may well have such a connection, which is why we use a "one tree" model here, but there's no current paper trail. However, she's one degree of separation from me in the popular sense--because I married her.

Answer 2

As Kylie has already pointed out "degrees of separation" are not necessarily the same as biological relationships. So 5th cousins could be only one degree of separation apart if they happened to be neighbors or married to each other. So the question is sort of like comparing apples to footballs.

The concept of "six degrees of separation" is based on any type of social relationship as explained here on Wikipedia. The whole concept is pretty simple mathematics. If everyone is socially connected to at least 100 people then six steps or 100⁶ is 1 x 10¹² or about 125 times the total human population. There is of course the problem of overlapping connections, many of the 100 people I know are probably also socially connected to each other, but given the sheer size of the final result it's still a pretty good bet.

Fifth cousins actually share 4th GGPs but we can't necessarily assume that they would be 12 degrees of separation based on social relationships since children don't necessarily have to have any social relationship with their parents. Many adoptees never even know who their biological parents are and many others go their entire lives not knowing that the man who raised them was not actually their biological father. One could argue that a parent child relationship is a social relationship regardless of whether or not the two actually know each other but I don't believe that adheres to the original concept of the six degrees of separation.

Comments

So, perhaps as an example (and I know you all will correct me if I am wrong, this week on the Global Family Tree Connection, we have F. Scott Fitzgerald, Bart Triesch and Henry VIII. For me:

1) F. Scott Fitzgerald is 18 degrees from me, but there was no blood relationship within that 18 degrees. When I search 30 generations, we were shown as 18th cousins through our shared 17th great grandfather Peter (Piers) Dutton. So, 18 degrees, but no real strong blood ties.

2) Bart Triesch is 20 degrees of separation from me. When I did the Relationship Finder, it showed that Bart and I are 20th cousins. We share Thomas Green as a 9th great grandfather. So further in non-biological relation according to degrees of separation, but closer genetically.

3) Henry VIII is 18 degrees of separation from me (non-biologically). Nothing showed up on Relationship Finder. Why? Because he has been dead for like 400 years (I didn't check his death date, only guesstimating). When I checked 30 generations, however, Henry VIII and I are 6th cousins (13X removed - in this case 13 generations). Edmund FitzAlan is Henry's 5th great grandfather and my 18th great grandfather.

Maybe this helps to understand the difference between non-genetic degrees of separation through F. Scott Fitzgerald married to Zelda, her father, his mother, her father, his mother, her mother, his sister, her father, his sister, her daughter (Elizabeth Gillette, now we are entering my territory) married Wm. Oviatt, their daughter Marinda had daughter Lucy Barber whose son, Jeduthan Baldwin who had son Leverett J. who had son Fred Leverett, who had son Leverett Frederick, who had me. This makes me separated 18 degrees from F. Scott Fitzgerald through his wife Zelda, but there is no biological relation.

Alternatively, I share a great grandfather with Bart, and a great grandfather with Henry VIII. Thanks for this mind-bending opportunity! Carol (Baldwin-3428)

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I think the confusion is based on the fact that the phrase "degrees of separation" has different meanings in different contexts. As it is used in genealogy the phrase typically refers to familial relationships, either by blood or by marriage. This is what Wikitree calculates as in Carol's example above and, I'm guessing what Alistair was thinking of in his original question. "Degrees of separation" has a very different meaning in regards to the concept of "six degrees of separation" which is an actual thing, a theory if you will, that all people on earth can be connected through six social relationships. In this context "degrees of separation" refers to ANY social relationship: friends, coworkers, members of the same book club, people you went to school with, etc. In this context two siblings could potentially be the most distantly connected people on earth and, conversely, the two biologically most distant people on earth could be just one degree of separation apart.

So in this context a woman born in Cambodia and adopted by people in New York might be six (or more, since no one has ever actually proven the theory) degrees of separation from her younger brother who she never met. But when she becomes friends with someone at work who is from Botswana she is now only one degree of separation from someone who could be as biologically distant from her as anyone on the planet.

It's all about the context. Time flies like an arrow, fruit flies like a banana...

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Hi Paul, Thanks for you very insightful feedback. 'Context' is important on many levels and in many situations. I need to remember that myself. Context is even included in languages (e.g., high [like Japanese] and low context [e.g. English] languages. I haven't heard/read the fruit flies comment in years! I remember an uncle telling me he was an artist...'he drew flies.' Carol (Baldwin-3428)

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So in theory we here are all within 1 degree because we have socially interacted with each other . Which in turn means I am within 2 degrees of anybody you have interacted with, and so on and so on.

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Well, technically Frigyes Karinthy who is credited with first proposing the idea in 1929 referred to "the network of personal acquaintances". But then that was 90 years ago when the population of the planet was only about 1.5 billion. So I suppose today with the population rapidly approaching 8 billion we might count this as a connection.

You can read Karinthy's short story "Chain - Links" here. It's only a few pages and actually quite interesting. Even though the population has more than quadrupled since then I think one could make a pretty good argument that the world has grown even smaller.

And thanks for the new line Carol, 'he drew flies' I love it! Think I'd have liked your uncle.

Answer 3

to give you another picture on the difference between connection and relation, I have a friend that I ''met'' through Facebook.  She is in Australia, I am in Canada.  We were in the same support group on FB, and as people do on there, became FB friends.  We shared various things over time, chatting about all sorts of stuff.  We found that we are both into genealogy for one thing.  Our ''connection'' is direct, 1-1.  Even if we have never actually met.

At one point, I was stuck with one line in my tree, and I mentioned it to her in one of our exchanges.  The names rang a bell with her, and on pursuing the matter we found that we were in fact distant cousins.  She is also on WikiTree, and the relationship finder puts us at 9th cousins officially.  But!  She is my cousin through her mother, while on my side the family connection passes through both my parents, 3 of my grandparents etc.  And when we get into the various connecting people, it isn't just one connection, it is multiple.  For instance, there are 3 sisters who came to Montréal in the 1650s, I am descended from 2 of them and my Australian cousin is descended from the 3rd.  Next generation, she has one sister in her ancestry and I have another.  And so on, there are as I say multiple connections.  We tried to figure out what the cumulative effect would be, and worked out that it probably makes us closer to 7th cousins from a genetic point of view.  I have lots of pedigree collapse in my tree, so much so that I tend to call it pedigree implosion.  

Answer 4

the "six degrees of separation" thing generally refers to living people, not deceased ones, and the general idea is that you can connect any two random people in six steps through social relationships. It sometimes works with deceased people, but not often. Wikitree's "degrees of connection" only goes through blood relationships and relationships by marriage, and not through social relationships. An example of this: Using Wikitree's connection finder I am 17 degrees from Queen Elizabeth II. Using social relationships (as in "met/knew X who knew Y who knew Z") I'm 6 degrees: 0 - me > 1 - my grandfather > 2 - his great-uncle Levin C. Handy > 3 - his uncle (by marriage) Mathew B. Brady (the photographer) > 4 - Edward VIII (who was photographed by Mathew Brady when he was Prince of Wales and visited the US) > 5 - George VI > 6 - Elizabeth II.