What a hoot! This is a story of discovery including the confluence of many facets of genetic genealogy. It’s a small piece of my genealogy, but it illustrates how many different tools work together. Here is a list of teasers….
1. A genealogy note from the 1980s
2. A Triangulated Group [12D24]
3. A DNA Match in TG [12D24] looking for her bio-father
4. Another DNA Match in TG [12D24], also searching for our Common Ancestor
5. An ALLEN Ancestor with a “sketchy” Tree.
6. My Ancestry focused on VA/WV, and nothing west of there
Without further ado – here’s the story.
The focus is on TG [12D24]. I have 88 different Matches in this TG, including a half 1C; a 2C; a 2C1R and a 3C1R. These four cousins are all on the same line from my father, to his father, to his mother, to her parents – OR: P,P,M,CA – OR: 2, 4, 9, 18 (using Ahnentafel numbers). A18 represents my Ancestral couple: John NEWLON b 1798 Loudoun Co, VA; d 1872 Harrison Co, WV and Marie ALLEN b 1805 Monongalia Co, VA; d 1882 Harrison Co, WV. Despite a lot of research among the other 84 Matches in TG [12D24], I’ve not been able to find a more distant Common Ancestor. FYI: John NEWLON’s parents were Thomas NEWLON 1767-1813 and Susan CUMMINGS c1772-c1805. I have found many Common Ancestors on these NEWLON and CUMMINGS lines. Maria ALLEN’s parents were Joseph ALLEN c1775-1848 and Elizabeth [maiden name not proved]. I have not found very many Matches with Common Ancestors on this ALLEN line – clearly ALLEN is a high potential for [12D24].
One of the Matches in [12D24] has been looking for her bio-father for several years. She recently found a good candidate and built a Tree for him. I found a Common Ancestor on her new paternal line – we are 4C1R on my SHIELDS/FINLEY line. Well… Per the paper trail, we are 4C1R on that line, but SHIELDS/FINLEY are on my maternal side, so I could not have gotten the [12D24] (paternal) segment from them. Dead end!
This points out the value of combining the genealogy and DNA – had it not been for the TG [12D24] segment on my paternal side, I might have been content to just accept the SHIELDS/FINLEY Common Ancestor couple, and not continued the search with much earnest. Worse – I could have gone down that rabbit hole, and searched the other 83 grouped Matches for those same lines…
Enter another Match in TG [12D24]… She and I had corresponded years before and tried to discover our Common Ancestor. She contacted me again, and also knowing our adoptee Match had now updated her Tree with new information, noted that she had an ALLEN in her Tree. I quickly checked – her Ancestors were: Garrett G MYERS 1850-1906 married to Lucinda ALLEN b 1856 IA (no parents).
Well, an ALLEN in IA was pretty far from my WV ALLENs… However, it was a potential surname link, so I researched some more. Lucinda’s parents appeared to be Joshua ALLEN b 1816 VA and Eleanor LANE b 1821 OH. OK, Joshua was born in Virginia – maybe this was the link. However, as I researched Joshua, all the Trees had him as son of Joshua, son of Joshua, son of (Joshua) Barnes ALLEN (and Eve SWIGER). I am well aware of Barnes ALLEN and Eve SWIGER as the parents of several children who intermarried with descendants of my BARTLETT line in WV – but they were not my Ancestors. And in calling up my old research notes on the Barnes ALLEN family, I did not show a son Joshua b 1816. This whole connection looked like: “well, all the first names look the same, and were in Virginia, and I don’t see anything else that might fit, so let’s just say that’s it.” My guess is that many of you have seen this kind of “genealogy research” before. And you’ve also seen virtually everyone else copy that same information.
You can call it a hunch, or confirmation bias, or whatever you want, but the fact that I had a TG [12D24] stuck at the 3C level, and probably going back on the ALLEN line, kept tugging at me. [NB: I wasn’t completely blind to the possibility that the link might be on ALLEN’s wife’s side.] I believe in DNA “magnetism” – the DNA tends to draw the puzzle pieces together, but I needed some more information.
So, I dredged up my old ALLEN research file – research that I had done in the 1980s. During the 1930s Depression, a Harrison Co, WV newspaper asked readers to submit Family Group Sheets. Many thousands responded. I remember going to an office in Clarksburg, WV filled with floor to ceiling bookcases with 5-inch binders filled with the Family Group Sheets (today over 30 microfilm rolls). I transcribed as many as I could over a 2-day period. Among my notes from that trip were the John ALLEN family. It was very sketchy – descendants reported some of his children and noted that several had moved away – including a note about son, Joshua ALLEN who “went west to Iowa, never to be heard from again”. Could this really be the Joshua ALLEN b 1816 VA, father of Lucinda ALLEN b 1856 IA m Garrett MYERS – great grandparents of my DNA Match who found her bio-father? If so, we would be 4C – a very reasonable relationship. And on my father’s side!
I quickly went to my list of DNA Matches at Ancestry and searched for ALLEN in Iowa. BINGO! I could trace at least 4 of them back to Joshua ALLEN b c1816 VA who had at least 8 children born in IA. None of my Matches knew the parents of Joshua ALLEN.
This looks very promising to me. Next steps:
1. Find some DNA Matches who descend from John ALLEN’s other children “who went west”.
2. Message Matches at other companies who are in TG [12D24], and ask if they had any ALLEN ancestors. I did this with two TGs from my HIGGINBOTHAM line and got several dozen positive responses. Many Matches at the other companies don’t have Trees, but I’ve found they are more likely to respond to such a pointed question.
3. Find some of my Matches who have Barnes ALLEN and Eve SWIGER ancestors, and ask them to search their own Matches for ALLEN + Iowa (I’m betting they won’t find Joshua ALLEN b 1816…)
You won’t have exactly this same confluence of facts. The point is to think about the possibilities with the information you do have and test it out. Make a reasonable assumption (a hypothesis) and try it out. Think about the way to reinforce it, and to refute it.
[23-38P] Segment-ology: Ahnentafel 38P – John ALLEN Family by Jim Bartlett 20220126
As readers of this Segment-ology blog understand very well, DNA segments are passed down from our Ancestors, through a line of descent, to one of our parents, and from that parent to us. Well… you might say: I thought our parents passed down whole chromosomes to us – 23 of them to be exact. That’s correct – and each chromosome is made up of many segments. Even the segments are made up of segments. While a parent passes down 23 chromosomes to us, those 23 very large segments, are actually made up of about 57 segments from our grandparents; and 91 segments from our great grandparents – see Figure 3 in my post “Crossovers by Generation” here. From a theoretical perspective, these segments can start and end anywhere and there are infinite possibilities. But for each of us, all of our segments are fixed before we were born – they are very specific in our body.
For this post, I want to look at the life of a DNA segment which is represented by a Triangulated Group (TG). You will recall a Triangulated Group is a segment of our DNA identified by a Chromosome, Start Location, and End Location – it’s a specific part of a chromosome passed to us by one parent. This is real DNA in our body – a long string of millions of base pairs, usually represented by over a thousand unique SNPs (which are the markers which are actually measured in a DNA test). We can “see” this segment of our own DNA because of overlapping shared DNA segments with various Matches. Because multiple Matches share the same long string of SNPs with us, we understand that this DNA segment had to come from a Common Ancestor (CA) to us, and to each of our Matches in the TG. The science tells us that that’s the only way we would have gotten such long segments in common.
So, exactly where did this TG segment come from?
Which of our Ancestors first had that segment – the Most Distant Common Ancestor (MDCA)?
Which generation back?
How was it formed?
What did it originally look like?
How was it transformed into the TG segment we now see?
Are some of our Matches in a TG actually related further back than the MDCA?
Are some of our Matches in a TG actually closer cousins than the MDCA?
Read on – all these questions will be answered in The Life of a DNA Segment.
Some ground rules – we are not talking about small segments – let’s use at least a 15cM IBD segment. This is not hypothetical DNA in a mathematical simulation of many possibilities and variations with some distribution curve. We are going to look at a specific segment that was identified by a Triangulated Group – it came from one of our Ancestors. We start with a real DNA segment in our body.
Let’s just start with an example and work from there. Let’s say my TG-segment is:
Paternal Chr 04 from 20Mbp to 45Mbp. My TG ID would be 04C2 – meaning it’s on Chr 04, starting about 20-30Mbp, and on my father’s side . [You can review ID codes here].
Let’s say it first appeared in a 3xGreat grandparent – specifically (to be generic, I’ll use Ahnentafel numbers): my father’s [A2], father’s [A4], mother’s [A9], father’s [A18], mother [A37].
Figure 1 – My Paternal Chr 04 and TG 04C2 on that Paternal Chr 04.
In order for a segment to have “first appeared” in A37’s DNA, it must have been formed from (usually) two separate segments. Let’s say such a recombined segment was passed down by A37’s mother, A75. A75 had two Chr 04s (a paternal one from A150 and a maternal one from A151.
Figure 2 – A37’s Two Chr 04s.
Figure 3 – A75 crossovers and recombination of her Chr 04
In this diagram, A75 is going to pass to her daughter, A37, the yellow segments, with crossover points at 35 and 115 (two crossovers, creating 3 segments, are typical on Chr 04).
Figure 4 – Chr 04 passed from A75 to A37
In this diagram, the top Chr 04 shows the grandparent segments passed down to A37 from her mother A75. There is no clue to the future TG. In the second Chr 04, I’ve overlaid TG 04C2, so we can track what the future has in store. It now has a crossover in it that makes the area of 04C2 unique – DNA from two different people. As we shall see, this area of A75’s DNA was passed down to me (after all, we started with a TG that I had). Also, some part of this area was passed down to others who became Matches in TG 04C2 because their overlapping shared segments meant these Matches matched me and each other.
Let’s continue with the Life of DNA segment 04C2… A37 is going to recombine the above maternal Chr 04 with the Chr 04 she got from her father (probably with two crossovers again), and pass the recombined Chr 04 to her son A18.
Figure 5 – Chr 04 with A37 recombination and passing to A18
The top two are A37’s two Chr 04’s with crossover points at 45Mbp and 95Mbp, with yellow (and blue) highlighting showing the three segments that are recombined to make the bottom row: a single Chr 04 being passed to A18. Note that the 35Mbp crossover point exactly coincides with the end point of TG 04C2. When A37 passes a Chr 04 to her other children, some may get the part the includes the imbedded 04C2 segment, and some may not. NB: This is a critical generation. At some point on Chr 04, we must have a crossover point at 45Mbp, because my TG 04C2 had that crossover point – this is the generation where that crossover occurred.
Next A18 will pass a Chr 04 to his daughter A9.
Figure 6 – Chr 04 passed from A18 to A9
Again, the top two rows are A18’s two Chr 04’s, this time with crossovers at 60Mbp and 160Mbp, with highlighting showing the three segments that are recombined to make the bottom row: a single Chr 04 being passed to A9. Note that neither of the new crossover points had any bearing on my TG 04C2 – in fact that whole end of Chr 04 (1 to 60Mbp) passed intact to A9, as part of her paternal Chr 04. Next we’ll see A9 passing a Chr 04 to A4.
Figure 7 – Chr 04 passed from A9 to A4.
In this generation A9 has crossover points at 20Mbp and 120Mbp. Other crossover points may be at other points for other children of A9. However, the 20Mbp is needed here (or in some generation for me to wind up with TG 04C2 [Chr 04: 20 to 45Mbp] – a unique TG segment made up of segments from A150 and A151.
Figure 8 – Chr 04 passed from A4 to A2 and from A2 to me
I just added a few more crossovers here – they don’t really matter as far as TG 04C2 is concerned. The crossovers had to miss TG 04C2 in order for me to get that particular segment. Remember this is not hypothetical, we started with a real example of a TG. The crossovers could have been different at each generation, but somewhere along the line, before TG 04C2 got to me, it had to be boxed in at 20Mbp and 45Mbp in order for me to have that TG. Because I have multiple Matches in TG 04C2, each of them had to have similar stories – they rarely get exactly the same TG I got, they got different segments from A37, but there was overlap in the area 20-45Mbp. If the other Matches did segment triangulation around this same area on Chr 04, they might have gotten TGs like: 15-35 and 18 to 42 and 27 to 53, etc. See The Anatomy of a TG here.
There are many, many ways the life of TG 04C2 could have played out, but they all would have resulted in a unique segment at Chr 04: 20-45Mbp, because a bunch of my Matches had overlapping/triangulating segments with me at that location. We started with the fact of TG 04C2 and all the included Matches.
With this TG originating in A37, I can have 4th cousins (4C) on my Ancestral couple A36 & A37 (the DNA coming, in this case, from A37). I could also have closer cousins, maybe some of them sharing more than just TG 04C2 with me. Can I have more distant cousins among my TG 04C2 Matches? Sure, I may well have a 5C Match on A150 OR A151, depending on which path the DNA came down. NB: a 5C could only share a maximum of 20-35Mbp from A151 OR a maximum of 35-45Mbp from A150 (because that’s all I got). I could have a 6C or a 7C on Ancestors of A150 or A151 – depending on which path the DNA came down. NB: none of my Matches has to share the full 45Mbp with me, just enough to have overlapping matches. I cannot share a full TG (20-45) with a 5C – this segment did not exist back that far.
Let’s see if we answered some of the questions:
So, exactly where did this TG segment come from? From Ancestor A37 [this has to be determined by genealogy research among the Matches in the TG – Walking the Ancestors Back – A37 was assumed for the purposes of this example]
Which of our Ancestors first had that segment? All of the Ancestors in the line A2, A4, A9, A18, and A37 had that segment, but neither A74 or A75 carried that entire, unique segment – A37 was the first.
Which generation back? 5th
How was it formed? By recombination of A150 & A151 DNA by A75, when she passed a Chr 04 to her daughter A37 [however, a unique segment could be created many different ways].
What did it originally look like? Originally, in A37, TG 04C2 was just a part of Chr 04. Review Figure 4 – A37 had a very large segments from A150 and A151.
How was it transformed into the TG segment we now see? Subsequent crossover points nibbled away some of the DNA, until only TG 04C2 remained.
Are some of our Matches in a TG actually related further back? Yes, on smaller parts of TG 04C2 some Matches could be 5C or 6C or 7C, depending on the ancestry of the A150 and A151 segments, and depending if the shared segments are large enough to form Triangulation).
Are some of our Matches in a TG actually closer cousins? It is definitely possible. It’s these closer cousins that help us to Walk the Ancestor Back.
With reference to the real possibility that some of the Matches in TG 04C2 may be more distant cousins (beyond A37)… What if A37 was a Brick Wall? Those more distant cousins would be on A74 or A75 or A148 to A151. AncestryDNA shows ThruLines Common Ancestors back to 6C (the level of A148), so it is entirely reasonable to expect the DNA to “work for us” back that far. Look at the Trees of those distant cousins for a Common Ancestor, and build out their children and grandchildren. The DNA has done it’s part, the rest is a genealogy task to find the link.
One observation is that TG 04C2 (20-45Mbp) existed in all 5 generations from A37 down to me. That is the unique string of SNPs exists in the area 20 to 45Mbp in each of those Ancestors – a pretty sticky segment to think about. All of my Ancestors back to A37 had to have those SNPs, and each of the Matches in the TG had to also have some part of them (enough to create a Triangulation).
So there you have it – the birth and life of a TG – you know the general process of what to expect.
The above was a top-down description of the Life of DNA Segment 04C2. We could also build the story up – starting with my TG 04C2, and describing what that part of Chr 04 looked like at each generation going back, until the whole 04: 20-45Mpb segment didn’t exist anymore. In this example TG 04C2 would exist in A37, and it would not exist in A37’s parents: A75 and A76.
I think most of our TGs will be found to have Common Ancestors at the 4C to 7C level; and some of the Matches in the TGs will have CAs back to the 8C or 9C level (maybe some even more distant). I think this is promising for genetic genealogists – many of our Matches will have Common Ancestors within a genealogy timeframe. We just need to find them.
Can weird or unusual things happen? Perhaps. I really don’t know. I understand that some ancestor had to have the TG segment and pass it down to me, and parts of it to my Matches in the TG. I understand the TG segment is pretty unique. And because it’s also present in multiple, separated, Match cousins, I’m confident that it’s from only one Ancestor. Is it possible that all of the multiple Matches are also cousins on another Common Ancestor? Technically, yes – practically, no! Maybe among my 372 TGs I’ll find a few that throw me curve balls. But, in the main, I’m confident that virtually all of my TGs will sort out. With my fixed set of Ancestors, and fixed DNA segments – there is only one correct way to interconnect them – there is only one way the DNA from my Ancestors came down to me.
SUMMARY for the Life of a DNA Segment – I know the above description is hard to follow (it was hard to write!) But the summary is that each of our TG/Segments started in some Ancestor, and was passed down to us. It was passed down through one, specific line of descent to a parent to us. When the TG/Segment was first formed, it was part of a full Chromosome in that first Ancestor. Somewhere along it’s journey, the Start and End points of the TG were determined by new crossovers points that are added when a parent passes a new, recombined chromosome to a child. Portions of each TG/Segment were also passed down to our Matches. Our TGs are formed by our shared DNA segments with those Matches. The final TG/Segment is a fixed part of our DNA.
Before I leave this topic, I want to refer to my recent post: TG SUMMARY spreadsheet, here. This spreadsheet lists all TGs. It also shows known CAs for each TG – and imputes missing Ancestors. With enough genealogy work, this spreadsheet clearly shows me Walking The Ancestor Back in each TG. By comparing the Ancestor Ahnentafel numbers in adjacent TGs we can see where crossovers occurred. I believe, in this TG SUMMARY spreadsheet, we’ll find the crossovers for the Start and End of each TG – indicating how and where each TG was formed. This spreadsheet could be a KEY interlocking process that leads directly to a full Chromosome Map linked to Ancestors. I’ll write more in a separate post.
[05F] Segment-ology: The Life of a DNA Segment by Jim Bartlett 20220104 Happy New Year