Using Triangulation Groups to Map My Wife’s Chromosomes

I would like to update the Chromosome Map I have for my wife. The one I have now looks like this:

This map is based on programming by Kitty Munson Cooper. It doesn’t look too bad. It only has 3 colors: 2 blue colors for her dad’s side and one color for her mom’s side. The red is based on the results from her 1/2 great Aunt. The blue is based on paternal grandmother cousins.

Here is Marie’s family of DNA tested relatives:

From bottom left to right we have the following that have had their DNA tested:

• Fred, Fred’s sister
• Pat, Buddy
• 1st cousin John
• 2 Paternal Aunts
• Dad and Mom
• Aunt Esther
• In addition I have results from a Dicks DNA study

The Rule of 1st Cousin, 2nd Cousin Combo

In my previous blog, looking at my mother’s side DNA, I came up with a rule. That rule said:

In a triangulation group between a person’s 1st cousin and a second cousin, the second cousin will be able to identify which grandparent the 1st cousins share.

I would like to apply this rule to my wife Marie as she has 1 first cousin and 2 aunts who have tested their DNA. These 3 are like cousins as the common ancestor of grandparent are the same. Marie also has 2 first cousins once removed tested. These would be similar to 2nd cousins as they both have great grandparents in common.

Basically, right now if Marie compares herself to John or her 2 Aunts Lorraine and Virginia, she doesn’t know if the shared DNA is from Estelle LeFevre or Edward Butler. However, a triangulation group (TG) with Fred, Fred’s sister, Pat or Buddy and John, Lorraine or Virginia, will show that DNA to be from Estelle LeFevre. Further, not just the match in common to the TG will be from Estelle, but the entire segment represented by Marie’s match to John or her 2 Aunts will be from Estelle.

That’s My Theory, Let’s Try It Out

I have a boatload of combinations to try this theory out on. First, I’ll go with Fred, Fred’s sister, John, Marie and her 2 aunts. First I go to Marie’s one to many menu at Gedmatch and I choose Marie’s relatives I just mentioned. Then I choose the Matching Segment CSV. This downloads a file of all the matches between these 4 people, making it easy to find TGs. I could have used the Chromosome Browser but that only hints at TGs. However, I will use the Chromosome Browser to focus my search.

Chromosome 14 example

The browser show’s Marie’s matches to:

1. Aunt Lorraine
2. Cousin Pat
3. Cousin Buddy
4. Aunt Virginia

Here is how I have the Triangulation Group (TG) beween these 5 mapped out:

This shows a Triangulation Group (TG) between Pat, Buddy, Aunt Lorraine. Aunt Virginia and Marie.

Now a few observations:

• The chromosome browser view above is from Marie’s point of view
• Marie’s matches with Pat or Buddy (#2 and #3 on the browser) represent the DNA they share from either Martin LeFevre or Emma Pouliot. It is also likely that one segment is shared from each of Marie’s great grandparents.
• These segments are represented in the Kitty Munson Cooper Chromosome Map at the top of this Blog.
• The long segment shared between Marie and her Aunt Lorraine is from one of Marie’s grandparents. Because Pat and Buddy also match Aunt Lorraine, we may say for sure that the segment Aunt Lorraine shares with Marie must have come from Aunt Lorraine’s mother Estelle LeFevre.
• Marie’s DNA she got from her grandmother Estelle is shown below.

The previous map had 2 blue segments on Chromosome 20 representing either of Marie’s paternal grandmother’s parents. We didn’t know which. Now it shows the one large segment taking up all of Chromosome 20 from her known paternal grandmother. The green should say Estelle LeFevre b. 1904 – not Emma Pouliot b. 1894.

chromosome 15

On Chromosome 15 here are the same people, but in the following order: Aunts Lorraine and Virginia, Pat and Buddy.

Interestingly, this time the program doesn’t overwrite the light blue. This is because the match for the light blue extends further than the match for the green. When I mouse-over the original map, it shows that the light blue match starts at about position 34 while the green match starts at about 35. Because of this, the entire blue match shows until it’s end and then the green match is shown.

This blue, light blue, green progression represents 3 generations of Marie’s ancestors on her paternal grandmother’s side.

Paternal Grandmother Results Using 1st Cousins, Once Removed

Here are the results of comparing Marie’s cousin and two aunts to her two 1st cousins, once removed. Here I correctly have Estelle LeFevre  b.1905 labeled for the green areas.

 

I didn’t bother doing the comparison for Marie’s X Chromosome. The reason is this. The X Chromosome that her dad gave to her, he got from his mom. That means that the green must extend for the whole X Chromosome. For that matter, the light blue would also be Marie’s paternal grandmother’s parents.

How to Identify Emma Pouliot?

That seemed to work well for Estelle, but is it possible to be go back one generation further and identify one of Marie’s great grandparents by DNA? I think so. Let’s take a look. This time, I don’t want to look at Marie’s 1st cousin John or her 2 aunts. The reason for that is that when I compare Marie to those 3 people, the common ancestor would be Marie’s grandparents. I want to compare Marie to her 2 first cousins, once removed to find her great grandparents – or in this case her paternal grandmother’s mother Emma Pouliot b. 1874 in the Province of Quebec.

We are using the same principle as before, but going one rung up the ladder. I will look for a Triangulation Group (TG) between Fred, Fred’s sister, Pat, Buddy and Marie. Once I find that TG, I will take the DNA match between Pat or Buddy and Marie and assign that DNA match to Emma Pouliot.

Chromosome 1

Let’s try this out on Chromosome 1:

1. Fred’s sister (2C,1R)
2. Fred (2C,1R)
3. Pat (1C, 1R)
4. Buddy (1C, 1R)

It looks like there should be an overlap between #1 and #3, but they have no match there in the middle of the Chromosome. However, on the right side, there is a match between #1 and #3. Using my plan, I’ll assign Emma Pouliot to the green segment. In this case, #1 and #2 representing the parents of Emma Pouliot are larger. It would stand to reason that these would belong to Emma also. However, for consistency, I will just map Emma to the green segment.

When I tried to map this using the Kitty Chromosome Mapper, it didn’t show up as Estelle had already filled up that slot.

Chromosome 2

This time the two 1C’s, 1R are on the top and the smaller segments representing Marie’s two 2C’s, 1R are on the bottom. Is there a TG? I lowered the gedmatch thresholds, which I didn’t do for the first part of this Blog. Here is the match between the 1C, 1R and the 2C, 1R:

They match on Chromosome 2, but a little below the 7 cM threshold. I’m not worried as I’ve read that in a TG a match is likely to be good down to 5 cM. That means that I will map Pat’s #1 green segment to Emma.

Unfortunately Estelle is taking up the space where Emma would be mapped on Kitty’s Mapper. This seems to be a trend.

Chromosome 13

I did the same exercise as above and mapped with no results. This time I took out the other references in the area of Chromosome 13 that were blocking Emma and got this:

Now we see Emma’s DNA in lighter green on Chromosome 13. The downside was that I took out some of Estelle’s DNA to the right of the light green area so Emma’s DNA match with Marie would show. Hey, I created this map; I can do what I want with it.

So that is what I found. My wife can claim hold to a lot of her grandmother’s DNA, but only 3 identified segments of her great grandmother’s DNA based on this procedure. Of course, one may say that every instance of finding the parents of Emma would be the same as Emma. Based on that idea, I’ll try another map.

This map isn’t really any better, it is just meant to show that whether you have the parents or the child, it fills up the same area on the map. Note I have the same problem here where Estelle fills up the older Emma DNA on Chromosomes 1, 2, and 13.

Marie’s Dicks DNA

The idea for this section should be more straightforward. I have been involved with a Newfoundland Dicks DNA project. There are many people who have tested their DNA and found through triangulation to be likely related to the Newfoundland Dicks family. For example, here is a list of the Dicks Triangulation Groups (TGs):

These include the Dicks TGs except for the most recent few. Joan is near the middle of the chart. She is my wife’s mother. All I have to do is see if Marie is in any of the same TGs that her mother is in. Then I can take the match with the other 2 from the TG and assign that DNA to the appropriate Dicks ancestors.

Here is what was added (in yellow):

All that was added was a probable Dicks segment on Chromosome 2. There were other Dicks segments but they were “behind” Upshall matches. That means that they are the ancestor of Frederick Upshall. The reason that the Chromosome 2 match stood out was that it was a match with Joan (Marie’s mom) and not with Marie’s great Aunt Esther (represented in red above).

Check Your Work

Fortunately, M MacNeill [prairielad_genealogy@hotmail.com] has looked at my wife’s family’s Chromosome 1. He has looked at the raw DNA which is more under the hood than what I am doing. Here is a small portion of his work. He phased Marie’s father and 2 aunts and then went back and put that information into Marie’s DNA.

The interesting thing about MacNeill’s map is that it includes the DNA for Marie’s 4 paternal great grandparents. The cross-hatched area is where it was not possible to determine the crossover point. At any rate, MacNeill points out some errors in my Chromosome mapping for Marie. He has sections of salmon or pink indicating Richard’s paternal grandparents where I have Marie mapped to Richard’s maternal side.

This is when I go back to my spreadsheet for the details:

In the first part of Chromosome 1, it is clear that Marie does not match Pat, Buddy, Fred, or Fred’s sister, so I cannot call that a TG or a Paternal grandmother match for Marie. My original rule said that Marie had to be in a TG for my segment extending plan to work.

Here is where I removed 2 paternal grandmother segments on Chromosome 1:

However, on the right of Chromosome 1,  MacNeill has more paternal grandfather DNA mapped where I again have paternal grandmother. In my defense, this was an area where, according to MacNeill, Fred and Fred’s sister appear to match on both the paternal grandmother and grandfather side. I couldn’t have known that as I only had information for the paternal grandmother side.

One other point on Emma pouliot

Above, I had mapped Emma Pouliot to Marie on Chromosome 1:

Here is a larger view of what MacNeill had for Marie’s family’s Chromosome 1:

The legend on the top line is difficult to read, but Pouliot is the darker red. More specifically, that would be Emma Pouliot. Marie is on the bottom line. The last vertical white line in Marie’s dark red area represents position 198. As I had mapped Emma from 197 to 207, that would put her in the end of the dark red area of Richard’s Pouliot maternal grandmother, before Marie’s DNA switches to the DNA she got from her dad’s paternal side in the salmon color. So at least my work agrees with MacNeill in this little area.

Summary and Conclusion

• Most of the additional segments came by phasing the unknown grandparent using the 1st cousins’, once removed shared DNA
• This method could work well along with the visual chromosome mapping that Kathy Johnston developed.
• There is a fine distinction with mapping the DNA of one’s known grandparent and mapping the DNA of the parents of that known grandparent. When mapping to the parents, the individual segments could be from either parent. When mapping to the known grandparent, that larger segment could contain compound segments of the parents. It is a subtle distinction, but one that should be maintained in my opinion for future research.
• Using the Kitty Mapping tool is fun and instructive as to how DNA works. It can be manipulated to show what one would like to be shown. For example, when I wanted to highlight the Emma Pouliot segment, I was able to do that.
• Even with no paternal and maternal grandfather DNA matches for Marie, I have been able to fill out her Chromosome map quite a bit – mostly on her paternal grandmother side.