The previous article in this series is Introduction To Using GEDmatch Part 2 (The One-To-Many Comparison Tool).
It’s taken me awhile to post another article in this series because I was hoping the Triangulation tool would be reinstated by now. Since it has not, let’s explore the People who match one or both of 2 kits tool that has recently been reinstated. For each of the matches we get to our kit using the ‘One-to-many’ matches tool, it is very helpful to know who else happens to match both of our DNA tests. This can help us begin to identify shared segments between at least three people, forming the basis for properly triangulating the segment back to a common ancestor, or set of ancestors.
Clicking on the People who match one or both of 2 kits link will bring up the People who match both kits, or 1 of 2 kits page. Enter your kit number in the first box, and the kit number of one of your matches in the second box, leaving the other three boxes as they are, and then click the Display Results button at the bottom.
Clicking the Display Results button will take you to a page that looks similar to the following screenshot (I have greatly shortened the lists in the second and third boxes to make it easier to view an example of the results page). It will take a bit of time (up to a few minutes in some cases) for this results screen to come up. If you have waited at least five minutes, and the results screen has still not come up, hit the back button on your browser, re-enter the two kit numbers and click the Display Results button again. If the results screen still does not come up a second time, the site is most likely busy and it is best to try again later.
Your results page will contain three boxes. The top box is the one we want to focus on. The kit numbers listed in this box match both of the kit numbers you entered on the previous page. These are very likely to be relatives, but you need to verify this by running a ‘One-to-one’ comparison between each of these kit numbers and the two kit numbers you entered on the previous page. Check the two ‘One-to-one’ comparison results to make sure the same segment(s) and chromosome(s) are shared between all three people. If so, there is a common ancestor, or set of ancestors, shared by all three people.
Contacting each of the people with shared segment(s) and chromosome(s), and comparing your trees is the next step to identifying who is the common ancestor, or set of ancestors. Even though you know there is common ancestry because of the shared segment(s) and chromosome(s), not everyone’s trees will extend far enough back to identify the connection. This is why using Genome Mate, or a spreadsheet, is essential to keeping track of your comparison data to keep referring back to as you continue to add new comparison results.
[A note of caution] For some unknown reason, using the People who match one or both of 2 kits tool does not always produce a complete list of the kit numbers that match both of the two kits you are comparing against. If you get a message saying “No usable match found between these 2 kits. Is batch processing complete?”, do not automatically accept this as being correct. While it is indeed possible that the batch processing on one or both kits may not be complete, there is also the possibility that the GEDmatch tool is simply not returning a match list. In the next post in this series, I will show how you can use a spreadsheet program (such as Microsoft Excel) to run your own comparison to verify the results of the GEDmatch tool, and/or provide you with a results list when the GEDmatch tool does not.
If you get stuck or experience any problems while following the steps above, or notice that a screen has changed significantly from what I’ve shown in the screenshots, please let me know by commenting on this thread or sending me an email. Thanks for reading.
The next article in this series is Introduction To Using GEDmatch Part 4 (Alternate Way To Find People Who Match One Or Both Of 2 Kits).
This article last updated 7 Oct 2014