Double Match DNA Triangulator

Double triangulation tool

double triangluation

Double Match Triangulator

There is a tool from Louis Kessler that you can download that should help you simplfy triangulation. From the website “This is an autosomal tool that allows the genetic genealogist to look at their autosomal data in a slightly different way than other methods. It assists by finding every segment from every matching person that double matches and additionally those segments that triangulate with two specific people, and produces an Excel file that contains a Map page containing all the matching segments and a People page listing all the people who match.” It combines two different people’s Chromosome Browser Results files from FamilyTreeDNA. If you have tested at FTDNA or uploaded your raw DNA from somewhere like AncestryDNA, you know that you are given a list of DNA relatives and there is a chromosome browser to use to compare your matches but it isn’t enough. When you triangulate results you are able to see the group of people that all match at exact chromosome locations. Triangulated segments belong to a common ancestor. Double Match Groups (DMG) are segments where a number of people have double matches and indicate common ancestors. There are also triangulated groups (TG) that have the same groups of common ancestors in common. The double match DNA triangulator will help to identify those groups easier.

According to Wikepedia “In autosomal DNA testing triangulation is the term used to describe the process of reviewing the pedigree charts of people who match on the same IBD autosomal DNA segment to see if a common ancestor can be found. The technique is best used in conjunction with chromosome mapping. Triangulation can be used going back many generations. However, well documented pedigrees are necessary for all the matching parties in order to rule out the possibility that the match is not on a more distant line which has not yet been researched. Caution still needs to be exercised when reviewing matches with smaller segments under 11 cMs in size, as many of these are false positives (identical by state).”

To read more about Triangulation, there are several great articles. Triangulation for y-DNA is a little different, this tool is for autosomal DNA testing. The definition given on the tool webpage is “Definitions:

“Double Match” is where “a matches c” and “b matches c” on a segment. Only if “a also matches b” on the segment is it a “full triangulation”, otherwise it is a “missing a-b” double match.
“full” is used with the term triangulation to distinguish it from the “triangulation” that many people incorrectly use to mean “a matches b” and “a matches c” on a segment and “c is in the in-common-with (ICW) list of a and b”.”

The tool is downloadable here.

About the author


I found my birth family after 40 years of looking for them. I used DNA tests, software to sort DNA match results, family trees, contacting DNA matches and several website tools. We want to provide you a "one stop shop" with all your resources to help YOU find YOUR family.

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