Joint Matches - Triangulation

You have one-to-one matches but it is possible that you both match another person. That would be interesting but maybe you match on different chromosomes? Investigation needed.

If all three of you match in the same place on one chromosome then you could be from the same original family. The significance of this is would be that all 3 of you have the same common ancestor line - for example you may relate to the father of the family and two others may relate to different children.

The caveat here though is that you have two chromosomes and may match on different copies of the same numbered chromosome? Then the scenario would be that your two matches are from different sides of your family OR you could both match on different sides of their family? See diagram below.

If the three of you match on the same place and same chromosome, there is a better chance of finding the common ancestor. Many people were able to get the chromosome match detailed locations into a spreadsheet. Once sorted you may find several people matching in the same location. This is a cluster and a cluster can include many people and more people = more clues and easier work? The segments do not have to be exactly the same length but ideally be very similar overlaps as in the example below.

Clustering

Website tools use the top matches for you and tests them against each other. Where it finds people who match and have matches in common, it makes a group or cluster. Each cluster needs to be researched for Common names, locations, trees and ethnicities. That can be a lot of people to write to. Take the biggest group or the most interesting and start there. For people who were adopted or have unknown lines and ethnicities this tool can help you work toward those goals. It is like the Leeds Method but companies do not use smaller matches and therefore may miss people who are more important to your research. The Leeds method also allows you to extend the reference document you make at any point in the future and it can sit in a single document on a screen or paper format.The cluster sytem needs a computer of some sort to use it on a regular basis.

Intermediate Matches

Sometimes your research suggests a DNA match should exist between you and someone else but no match is found? Then you need to see if there is an intermediate match. GedMatch provides a tool for this and your DNA testing host probably has one too by now. MyHeritage calls it 'Shared Matches' and 23andMe, 'Relatives in common'. If you contact the intermediate and share notes and stories it is possible to narrow down the connections of how the three of you are related by surnames, geography and timelines.

GedMatch does this for you as do other sites. Put your kit number and the other persons DNA into the "People Who Match both of 1 or 2 Kits Tool" and it will generate a list of any third party DNA matching both of you and the other person, from the millions of members.

Please note that It will also give you contact details to enable you to write and introduce yourself. BUT before you do that, you MUST take each kit number of interest and run a one-to-one test to make sure that the result is true!

This site aims to be complimentary to other sites with similar aims.

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