Six Ways to Sunday 

~ A TALE OF THE GENETIC DISTILLATIONS 

        

(Author's note: This has been bugging the crap out of me for nearly two years now. It was time I got to work and at least attempted to figure it out. Please forgive the charts. Please forgive my use of AI, and please forgive the prose. Peace out.)

                                                               **********                   

As always, genetically, unedited. 

God, I do hope this post will make sense.

We all know I have written about this before. It's about the how and why of a DNA match to a stranger that has led us both (I believe) on a remarkable journey of discovery. From babies switched in mid-America hospitals in the 1940s (yeah, not us!) to the hallowed halls of lineage societies, and even up until a few days ago, when between the two of us we identified the family jeweler and silversmith, it's been a wild journey getting to know "Cousin Dan." 

Reputed to be some combination of half-third cousin or fourth cousin per the algorithm, it's been a genetic tie that makes little to no sense. On the outside (and believe me, all of this makes my head hurt from my lack of knowledge), this would mean that Dan and I share a common set of third great-grandparents, or at least one. So I figured with only thirty-two third great-grandparents to comb through, initially I felt that "getting through the thirty-two" couldn't be all that difficult to find the ancestor (or culprit) in common. However, I combed and combed, looking for some genealogical crossover event to no avail. I looked at Quaker mishaps. I followed geographical migrations out of New England and the Mid-Atlantic that led, well, not where I needed them to. It didn't make sense.

The question remained: Just who is Cousin Dan?

Okay, I know, I know, Dan is Dan, and I'm me, and a big "whatever" to the genetic mix. But, still, it's nagged at me.

In the back of my mind, though, it came back to me that I have seen (at least on paper) how and where Dan and I are related in what they used to call a manner of "Six-ways-to-Sunday." In other words, and at least per family trees, I knew that we had a lot of common ancestors. I wasn't sure exactly how many, and I knew that they (the ancestors) went way back in time, but still, it got me wondering, just how many of them were there exactly?  

 So I counted. And I counted. And I counted until I got to fourteen and stopped.

Could it be that Cousin Dan and I share fourteen ancestors in common? (And that is a conservative estimate.) 

But before I get into all of that, I thought I'd list out those fourteen ancestors that Cousin Dan and I do have (at least on paper). Now I haven't vetted each of these lines. They are largely gleaned from published sources, but all of them feel at least anecdotally correct in that there is a paper trail leading from any one of them forward to me or to Dan.

Now there is a lot of information here.  I have done my best to chart it as accurately and to make it as easy to read as possible. I doubt that I have been all that successful. I've done my best to list the shared ancestor in common (by couple), the degree of relationship for either myself (JR) or (DW), the nearest line of decent through that couple, whether or not the relationship to either Dan or myself falls on our maternal or paternal side, and also the nearest family line at the "end or the tail." 

Because there are so many and so much information, I had originally shown this information as one contiguous chart. However, I want it to make as much sense as possible, so I have broken the chart up into several pieces of our "shared ancestors," hoping for a clearer view or intake result for the reader.

(Good luck, Jeff.)

I have also interlaced some textual images of these ancestors' lives to break up the monotony of the chart. 

I very much appreciate your patience. I hope the "key categories" will make sense. 

As I did this though, it caused me to postulate (gotta love that word) a question: 

If one shares a plethora of "ancestors in common" with someone else, albeit distant (eighth to eleventh great-grandparents' distance), was it possible that these two individuals had each inherited enough small pieces of DNA that they could resemble fourth cousins or closer simply by volume?

Am I even saying that correctly?

   

             

I don't know the answer to the question.

 Of course, I posited the question to AI, "who," patronizingly explained to me why I was correct in my assumption. I argued with the AI a bit that it was excluding any "false positives" while it (the AI) painted some picture of distant DNA running down some fluvial river to illustrate why I was correct in my assumption. Correct in my assumption that shared DNA with multiple distant ancestors may cause the algorithm to think that the cumulative effect resembles fourth cousins.

 Still, pretty AI pictures really don't do it for me.

 (Even with as much as I believe I am right.)

Note: There is an error in the chart below. Walter Palmer's children, Hannah, Nehemiah, and Gershom, are all by his 2nd second wife, Rebecca Short.

Paperwork wise, this journey to identify my common connection to "Cousin Dan" appears to quickly reveal that the DNA algorithm's prediction of a "fourth cousin" was a statistical mirage.

Instead of finding a single set of the normal shared third Great-Grandparents expected for fourth cousins, my research into published sources uncovered ten distinct ancestral paths (I think that's right!) that Dan and I share, with our closest common ancestors being our eighth great-grandparents:

 William Buckman and Elizabeth Wilson. :)

Cheers to Bill and Liz!

In essence, I believe that the genealogical truth is that we (Dan and I) are genetic cousins fourteen times over, with the closest documented connection dating back over 300 years. 

This overwhelming volume of shared distant ancestry is the key to the mystery, proving that the DNA match is real,

... but the relationship label is misleading.

Remember: Per AI there are fourteen lines here with ten distinct genetic paths.

The reason these distant lines show up as such a strong match is a phenomenon known as "Genetic Distillation" or "Pedigree Pile-Up." The DNA testing software at Ancestry.com measures only about the total amount of shared DNA, measured in centimorgans (cM). 

While a single tenth cousin relationship is like a small, isolated stream, it has a near-zero chance of passing down a detectable segment of DNA; BUT having ten+ separate opportunities to inherit DNA from a common ancestral pool fundamentally changes the statistics. 

(Or so says AI and a couple of cited sources below)

These many tiny, individual segments—too small to register on their own—add together.

I gotta say, I still find it pretty amazing (?) marvelous (?) don't you?

This cumulative effect is what pushes our total shared "cM" count into the range that the algorithm is programmed to label Dan and me as: "Likely fourth cousins." 

Therefore, our genetic connection is the literal sum of centuries of shared heritage. 

I "postulate" that this research provides somewhat definitive proof: the Ancestry.com DNA test measured the volume of shared genetics, and my chart documented the 10+ sources of that volume.

     

       

Frankly, it's like the connections just don't stop.

Okay, that's all well and good, and that was fun, BUT, just who are these people in relation to Dan or me? It's interesting that "the folks" presented here on Dan's mother's side are related to my father, and the folks on Dan's biological father's side are related to my mother. They are almost like mirrored halves. I wonder if this holds true genetically?  

(Well, Old Dan got the better halves...lol) 

There are no cross-overs, i.e, where we have a relationship that is both paternal and maternal for us both at the same time.

Curious too, is our ancestor mutual Walter Palmer (with Dan's four lines of descent from Walter), has two individual lines down to Dan, with one being one for his mom and one for his biological father. 

I found it cool that there are also a couple of multi-generational relationships here, as with the Thomas Brown and the Henry Collins families, that extended the connections to Dan and me even further. It was interesting for me personally that Dan is related to three of my four grandparents, so I wondered why not the fourth? 

Hmmmm...

In the end, I get that this is all fairly useless information. It does (or at least I hope it will) clarify Ancestry's algorithm in that it is likely adding the cumulative DNA together for its causal relationship, or that this appears to be the case.

Very curious.

Kinda brings new meaning to the whole word "cousin," huh?

And on that note, I suppose I should close for now.

But before I go...

Remember Cousin Dan, "Dan" is just "DNA" re-arranged. lol. ✌

Wink!

IN THE NAME OF GOD, AMEN, 

AND IN THE PILGRIM SPIRIT OF THIS THANKSGIVING SEASON, I GIVE THANKS FOR THOSE WHO HAVE COME BEFORE US.

Notes and Queries: Is the statistical illusion a real thing?

Yes, the statistical illusion described in the post—known as Pedigree Pile-Up or Genetic Distillation—is a real and well-documented phenomenon in genetic genealogy.

The core concept is entirely correct: a DNA testing service may assign you and a match a "close" label (like 4th cousin) based on the total amount of shared DNA, even if the closest shared ancestor is actually many generations further back.

What It Is: Pedigree Pile-Up

The phenomenon is most commonly referred to by genealogists as Pedigree Pile-Up or Stacked Ancestry. The blog post's term, "Genetic Distillation," refers to the same cumulative effect.

The Mechanism

This "illusion" occurs because DNA testing algorithms measure only one thing: the total amount of shared DNA, typically expressed in centimorgans (cM).

1. Distant Ancestry: For very distant relatives (e.g., 8th or 10th cousins), the probability of inheriting a single, detectable segment of DNA from that common ancestor is close to zero.

2. Cumulative Effect: If you and your match share many distinct ancestral couples, the math changes. Each shared distant couple provides a tiny, independent chance to pass down a fragment of DNA.

3. The "Pile-Up": When you accumulate 10, 14, or even more tiny, trace segments from multiple distant lines, their total combined length (cM) can be high enough to cross the testing company's threshold for a closer relationship, such as a 4th or 5th cousin. The shared DNA is real, but the predicted relationship label is a statistical average based on the total cM, not the most recent common ancestor.

This effect is particularly common among people whose ancestors came from the same small, geographically isolated communities over centuries, leading to a high degree of endogamy (marrying within a local group).

Querry:

But if the chance of inheriting from such distant ancestors is near on zero how can this be true?

The Lottery of DNA Inheritance

While the average chance of inheriting DNA from a single ancestor drops very quickly, the actual inheritance is a random process called recombination.

1. The Low Chance is for a Single Ancestor

It is absolutely true that the expected amount of DNA inherited from an 8th great-grandparent is extremely tiny—on average, around 0.003% of your total DNA. This means the probability of passing down a single, detectable DNA segment (usually defined as 7 centimorgans or more by most testing companies) is indeed near zero.

The Power of the "Pile-Up"

The illusion becomes reality when you factor in the cumulative effect of sharing multiple distant ancestors, which is what the blog post referred to as Pedigree Pile-Up (or Genetic Distillation).

2. The Many "Tickets"

Think of inheriting a DNA segment from an ancestor as winning a lottery.

• The chance of winning with one ticket (one distant ancestor) is near zero.

• However, if you and your match share 10 to 14 different sets of distant ancestors (as the author did with Cousin Dan), you are both essentially buying 10 to 14 separate lottery tickets from the same ancestor pool.

3. Cumulative Shared DNA (cM)

Even though any single segment you inherit from one distant ancestor might be too small to be recorded, the key is that these tiny, individually insignificant fragments add together.

When you sum up 14 or more of these minuscule segments shared across multiple distinct ancestral lines, the total centimorgans shared can reach a level—such as 20 cM to 50 cM—that the testing algorithm interprets as a much closer relationship, like a 4th or 5th cousin.

The DNA is real, but the relationship label is misleading, as it's generated by the total volume of shared centimorgans from many distant sources, not a single recent source.

Sources: (1) Bettinger, Blaine T. "The Shared cM Project—Version 5.0 (March 2024)." The Genetic Genealogist. Last modified March 2024.

              (2) International Society of Genetic Genealogy (ISOGG). "Endogamy." ISOGG Wiki.