Gedmatch triangulation utitlity and "popular" ancestors

[Frederator]

Just started playing with the Gedmatch triangulation utility. Think I may be seeing some interesting results, but would like to hear others' stories in order to get a more complete appreciation of its use.

So far there have been no magic bullets. I have only 1 non-speculative match, either at FTDNA or Gedmatch. That guy's pedigree (like everyone else's) isn't perfect, but one version contains 3 possible connections ranging in the mid-to-late 1600's.

While those possibilities seem to be contradicted by alternative versions of the pedigrees floating through the ether, there is an uncannily frequent occurrence of others on the triangulation page who also claim ancestry from 1 particular MRCA candidate.

Should I be excited about this? Like I said, the MRCA is in the mid-to-late 1600's. I suspect this may simply be an artefact of folks cramming in "popular" ancestors to a pedigree without a super amount of research. I've experienced a lot of weird "coincidences" in researching matches before. Like the fact that one of the "closer" matches shared my same surname but upon closer inspection turned out to be adopted, with thorough DNA evidence to prove it.

Also wonder if the pattern of matches could equally be due to coincidence rather than shared descent through a single common ancestor. While there are some definite "bottlenecks"--some folks more closely related through the same line--the volume of people we're talking about seems to defy wrapping it all in a tidy package. To my knowledge I share no plausible common ancestor with any of these folks more recent that late 1600's Europe. The world went from 600 Million to over 6 Billion during that time.

Any personal stories confirming/refuting connections made through triangulation?

[djparlette]

I don't know if this is much help to you , but when I study my triangulation results from here I often see the names of people either me or one of my siblings share genomes with at 23 and me, even though they are not a match with me here. One of these people and I share at least 4 colonial ancestors.

[Frederator]

Interesting. If I understand you correctly, you have definitely confirmed remote-ish ancestry with a few of them.

The weird part may be in the effect of differing algorithims at FTDNA vs. 23&Me. I don't think anybody knows the full low-down on what those differences are--and there are probably many, specific to individual chromosomes and locations on the chromosomes. I have only tested FF, so I don't have any direct basis of comparison.

Still, sounds like the definitely-connected people who show up on triangulation are probably projected on the more speculative end of the range, rather than 3rd or 4th counsins, no?

That's fairly consistent and relevant to the scenario I'm currently contemplating. It'd probably be more shocking to find a valid triangulated relationship that was like definitely 3rd of 4th cousin.

I don't know if this is much help to you , but when I study my triangulation results from here I often see the names of people either me or one of my siblings share genomes with at 23 and me, even though they are not a match with me here. One of these people and I share at least 4 colonial ancestors.

[MoberlyDrake]

I keep wondering about the triangulation tool because I find that so many of the people who match me have the same names (of people who do not match me) in their lists. It gives me the impression that everyone who has taken the test is related to everyone else! How reliable is the triangulation tool?

D Parlette,

You are one of them! You do not match me, my Mom, or my cousin. BUT you match 7 people who match me, and if you are the same person as DParlette (I suspect that is a relative's account that you are managing) you match someone who matches both myself and my mother.

Should we be comparing trees even though we don't match each other?I have lots of examples like this!

Carol Anne

[Frederator]

I hope that you and dj are able to connect through PMs and whatnot. Sounds like you may have some interesting connections.

But I'm not sure it's a question of how reliable the triangulation tool is, though. I suspect that in general people have more common ancestry than we'd imagine. At least the sort of person who does genealogical DNA testing--lots of Ashkenazim and Americans with colonial ancestry.

I suspect it's more a question of understanding the limitations of the triangulation tool. Best case scenario is probably to test multiple family members from various branches and generations, so that you don't necessarily need the triangulation tool as such.

That's not always going to be an option, though. Like my case. And I wonder if I might just possibly be the kind of guy who actually gets some benefit out of the triangulation tool--all European ancestry, but little or no colonial ancestry. I'm not being swamped by hundreds of matches.

Of course it's an unhappy situation to be an "early adopter" from one of the populations that isn't well represented in these databases, like East Asians. No matches at all. Maybe just as frustrating is the person with literally hundreds of colonial or Ashkenazi ancestors with little hope of unwravelling the myriad of shared relationships.

Triangulation probably works best with folks with thoroughly researched pedigrees or at least very few colonial or Ashkenazi connections.

I keep wondering about the triangulation tool because I find that so many of the people who match me have the same names (of people who do not match me) in their lists. It gives me the impression that everyone who has taken the test is related to everyone else! How reliable is the triangulation tool?

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