My Heritage DNA has recently added the capability to automatically triangulate segments between DNA matches. I am very, very excited about exploring this new feature. It’s going to save all of us so much time and effort searching through our matches. In this post, I’ll explain a little bit about what triangulation is, and how to access this feature on My Heritage, and how to use the information for your genealogy research.
I can hardly contain my excitement, and I know exactly how I will be spending my extra time over the next few weeks. I hope that this feature is equally exciting and helpful for you!
What is triangulation, anyway?
The word “triangulation” has two meanings in the genealogy circles. It is sometimes used to describe the process of using family trees in order to find the common ancestor among DNA matches. It’s fine to use this word in this way, but there is actually a more technical, DNA-oriented definition of triangulation. When you have a DNA match, it means that you and your match have at least one detectable segment of DNA that is at least half-identical. Genetic genealogists can use these DNA segments, shared among multiple matches, along with (hopefully) well-researched family trees, in order to determine a common ancestor.
The idea is to try to figure out from which ancestor you inherited a particular DNA segment. Once you’ve figured out which ancestor “gave” you a certain DNA segment, any time you see a new match that also matches on that segment, you can assume (sometimes) that they are also related through the same ancestor (whose identity you already determined).
How to access the triangulation feature on My Heritage DNA
To start off, I always recommend sorting your DNA matches by “Largest Segment”. While this doesn’t guarantee that you are most closely related to the people at the top of the list, this is the best way to avoid DNA matches with whom you share only small segments. Small segments could mean a very, very distant relationship – too far to reliably trace – or even no relationship, since it is possible to have DNA segments that are just coincidentally identical (identical by state).
If you can, choose a relatively close cousin that you already know how you are related to. For these instructions, I am using my mom’s DNA results, and I’ll choose her first cousin on her dad’s side. It’s great to choose a first or second cousin, if you can, since you will already know which line of your family that you match on. It’s not foolproof, but choosing a 1st cousin eliminates 50% of the lines on your family tree because you know which grandparent you match on. Choosing a second cousin is better because it eliminates even more of your family tree when looking for common ancestors.
If you don’t know how any of your DNA matches are related to you, or you aren’t sure, you can still use triangulation. In fact, it is extremely helpful. You’ll just have to use segments to search for common ancestors among your matches who do have family trees, which can help you learn more about your own family tree.
Once you’ve chosen the match, click on the “Review Match” button on the cousin that you want to triangulate with:
Once you are on the Review Match page, scroll down just a bit in order to see the DNA matches that you share in common with your chosen match. If there are available triangulated segments, you will see an icon to the right of the shared match’s name and estimated relationship to your match that looks like what you see in the red rectangle in the image below. Click on the icon!
Once you clicked on the triangulated segment icon, your browser should have opened up your chromosome browser. At the top of your screen, you will see a summary of your shared DNA with your close cousin match, plus the cousin who you are trying to triangulate with:
The final bit of information about your triangulated segment can be see when you scroll down within the chromosome browser. In this example that I am using, I can see that my mother, her first cousin, and this mysterious match share a triangulated segment of 28.9 cMs on chromosome 10. This is a great segment (the size!), and likely means a not-too-distant common ancestor between these three relatives.
My next step would be to see if my mother matches anyone else on this segment, and try to identify the common ancestor. I have another clue about my the probability of this match from the shared ethnicity that this match has with my mother. Allison has no Eastern European, so it leads me to believe that their common ancestor is probably a great-great-great grandfather or closer, and is on my mom’s grandmother’s mother’s side of the family. I can check through more shared matches and their trees to find out if I am right.
Tip: A spreadsheet is a great way to keep track of DNA segments and triangulated matches.
I hope that this post has helped you understand a little bit about what triangulation can do for your family tree research, and how to access and use this feature on My Heritage DNA. I would love to hear from you in the comments if you have tried this triangulation feature, or have any questions about something that you have read here.
I try not to get too technical on this site, since I want to make sure that all of my posts are accessible and understandable for beginners, but if you want to know more about advanced topics like this, you can read about chromosome mapping and triangulation strategies.
Thanks for stopping by today!