A new Triangulation Group (TG) is big news. Perhaps not on the scale of a discovery on Mars, but on the level of Irish Frazer Genealogy and DNA research it is. Triangles have been studied since antiquity. Pythagoras did a good job of analyzing them. He came up with the Pythagorean theorem. There was also a whole philosophy based on his beliefs. Here is Pythagoras wearing his favorite tablecloth.
One of the more important things about triangulation, is that it can be used to find things. Given 2 distances and an angle, the 3rd distance can be determined. This may be helpful in determining the height of a tree which is otherwise difficult to measure or to find someone lost at sea.
Triangulation with DNA
With DNA, triangulation employs a similar concept. When 3 people all share the same segment of DNA and they all match each other on that same segment, that is what we call a Triangulation Group (TG). This means that there was a couple who lived at one time a long time ago and a portion of their DNA broke off as they had children. That same portion broke off into smaller pieces in different directions through the ages and came down to their descendants today and was still identifiable by the fact that there was a match between these 3 testers. I find it quite amazing that this would even happen.
The Existing Frazer Triangulation Groups
Everyone has Triangulation Groups. These are groups that indicate that, among your DNA matches, there are common ancestors. However, it is difficult to determine which common ancestors those TGs represent without a reference point. What we are trying to do in this Frazer DNA project is identify specific ancestors based on known Frazer genealogy and known DNA matches. The first 2 Frazer TGs consisted of descendants of Richard Frazer who was born around 1777.
When we first found the 2 TGs, there were only 3 testing families in the yellow, blue, and salmon lines that knew they had Richard Frazer as an ancestor. However, testers in the purple and green lines above also were in the TG. We discovered that based on some of the genealogy we had, that they would fit well in the Richard line. This is where we used the triangulation. We used the genealogical principal of going from known (the known descendants of Richard Frazer) to discovering what was unknown (placing 2 triangulated families into the Richard line who were unsure of their genealogy).
The fact that I had my 2 sisters tested for DNA helped in finding these TGs. In places where my DNA was missing in a match, it was possible to find matches in one or both of my sisters. I’m in the blue Hartley line above.
The New Frazer TG
The new Frazer TG represents Archibald Frazer, the brother of Richard above.
Actually, the DNA from the TG could’ve also have been from Archibald’s wife, Ann Stinson. But all the children were Frazers, so we’ll go with that for now. Due to cousin marriages, 2 of the families above were also in the Richard Frazer Triangulation Group. I’d like to thank Doug for testing as it was his recent test that brought out the crucial third match of this new TG. He had low to moderate expectations for his results based on the chart below. However, his testing paid off in what has been called the gold standard of DNA – a new Frazer TG.
Now, out of these 6 DNA testing Frazer families, only 3 made it into a TG. Why is that? One answer is random chance. The other reason is that due to the distance of relationships represented in the chart above, the chance of even having a match goes down.
Many of the Frazer descendants that tested for DNA were at the level of 4th cousin or 4th cousin once removed. At that level, the chances of matching could be at 50% or less. So I suppose that it makes sense that only half of the testers made it into the new TG.
Here is what the new TG looks like on my spreadsheet:
This tells us that Jane, DV and MFA all match each other. That is the TG. They match on Chromosome 4 for about 8-10 cMs along the position from about 162,000,000 to 174,000,000. These 3 are related at no closer than 4th cousins. In the chart above, Jane is the dull green colored line. DV is in the bright green line and MFA is in the Salmon colored line.
What About the 3 Testers That Are Not in the TG?
Does that prove that they are not descended from Archibald Frazer and Ann Stinson? No. They match each other by DNA singly, but, as mentioned above, due to the way the DNA came down, they didn’t happen to be in the 3 way matching TG.
- This new TG solidifies years of research and gives DNA proof of the work done in this Archibald Frazer/Ann Stinson Line.
- Others who have already tested may be found to be in the same TG. They would be relatives in this line or perhaps a line that precedes this one. They may or may not have known of their Frazer or Irish ancestry.
- For others who have not yet tested, it may help prove or disprove the research that they have done once they do test their DNA.