4

It's a real pain to try and find the triangulated matches that I share with another DNA donor. I might have to click on "show more DNA match" ten times before I see one triangulated match.

enter image description here

Is there a way that I can view just the triangulated matches?

5

No. MyHeritage DNA does not currently have a way to view just the triangulated matches. You have to find them yourself, remembering that if you have even one extra person on a segment that does not triangulate with the others, then the triangulation will not show up.

This is what I recommend you do:

  1. Download your DNA Matches shared segments. You can do so from the Advanced Options dropdown on your DNA Matches page.

enter image description here

  1. That produces a .csv (comma delimited) file that you should then load into Excel or other spreadsheet program.

  2. In your spreadsheet package, you should sort your segment matches so that they are ordered first by Chromosome, 2nd by Start Location, and 3rd by End Location.

  3. Then take a look at specific segments you're interested in, e.g. significant segments that match to specific known relatives that you are interested in.

For example, I share a segment with a 2nd cousin on my father's father's side on chromosome 2 between start location 119,612,264 and start location 168,646,041 (43 cM)

(This relative actually tested at 23andMe, but my paternal uncle matches me on the same segment from 119,751,997 to 171,075,377, 45.9 cM, so I can use him instead.)

Here are what the matches will look like in your spreadsheet. I've yellowed in my match with my uncle:

enter image description here

  1. Go to the One-to-many chromosome browser and add the relative you're matching to. Then one at a time, add the other people who overlap on that segment.

If they match on the segment with you and your known relative, then you'll have a triangulation box. Then leave them there. If not, remove them and try the next person. I'd suggest starting with your largest matches on the segment first and working down in size. Keep this up until you have gone through all your overlapping DNA matches, or until all 7 DNA match locations filled. If you fill all 7, then remove the last one to try the ones left.

e.g. I was ably to find 3 other people in the same triangulation group as my uncle (and thus my 2nd cousin) so these 3 people will all be related to me on my father's father's side and we will all have a common ancestor, possibly quite far back, that passed this segment to us.

enter image description here

Remember that you must add people one by one and always start from a group of people that triangulate. If you add more than one person and you no longer triangulate on the segment, you won't know which person was the one not matching.

While I did this, I found that the majority of my DNA matches who overlap on this segment did not triangulate. They may either be matching on my other chromosome (from my mother), or might be by-chance matches.

MyHeritage DNA tends to have more and larger by-chance segment matches than other companies because they impute and stitch their matches together which results in more false positives. So this step-by-step triangulation is a great way to eliminate most of the false positives and get good triangulation groups. You'll need at least 4 people (yourself and three others) to prove that they are all triangulating on the same chromosome. For any pairs of siblings, you'll have to add another person, because the siblings could be fully matching each other and thus not count as separate points.

So the MyHeritage DNA chromosome browser don't have anything that does all the work for you. But be happy that it confirms for you individual segment triangulations. This is much better than what the other DNA companies provide. It is also much easier to do this at MyHeritage DNA than at GEDmatch where you have to do the one-to-one compare of each person manually.

And it may even be good that you are forced to do this one by one. You'll get better insight as to how the pieces of your DNA are built up and how the ancestors passed them down to you.

Of course, if MyHeritage DNA would automate this for us, nobody would complain.

  1. You could simplify the work of testing each match one-by-one if you use a tool such as Double Match Triangulator (DMT) to first find all your triangulations. To use it, you need your segment match file and the segment match file of at least one other person.

Here, for example, I compare my matches with my uncle's matches using DMT:

enter image description here

DMT immediately shows me the 3 triangulating people I found through manual labour above, as well as 3 others. I now know the 6 people that likely form a triangulation group.

But when I put all 6 together in the MyHeritage DNA Chromosome Browser, they are not shown to triangulate together, even when I lower the limit to 2 cM. This indicates one problem with the MyHeritage DNA's marking of triangulations. They must first be looking to see if all the people match each other, and only if they do, will they then check the individual segments for overlap. This is unfortunate and will cause you to miss some valid segment triangulations if you only use MyHeritage DNA's Chromosome Browser to find them.

| improve this answer | |
  • 1
    Very good answer, @lkessler. It's really unfortunate that MyHeritage doesn't offer this option, which would make it much simpler. I have checked out your DMT and think that it will be the simplest semi-automatic option for finding triangulated matches. The biggest problem with both the spreadsheet and the DMT options are, that you are constantly downloading new files to keep your database/information up-to-date. (Sometimes it feels like I'm spending more time updating my spreadsheet then comparing and analyzing the data.) – TJinBC Apr 16 '18 at 22:57
  • @TJinBC - You only have to download new files if a new relative tests who you absolutely need to analyze. Otherwise, the other new testers who are distant relations aren't going to add much to your analysis, since you'll have plenty of people already that distant that you can use. Don't worry about missing a few triangulations. It's the analysis of what you've got that's more important than trying to keep everything perfectly up to date. I usually update my own segment match files only once or twice a year and I hardly ever have found the need to update the files I get from my relatives. – lkessler Apr 17 '18 at 0:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.