Triangulated segments are shared DNA segments that you and two or more DNA Matches all share with each other, and therefore likely all inherited from a common ancestor.
The best way to identify triangulated segments in the One-to-Many Chromosome Browser is to compare yourself, a known relative, and one DNA Match, to figure out which part of your family tree that DNA Match is on. If none of your known relatives have taken a DNA test, this is a good time to get them their own DNA kit!
Identifying groups of people on your DNA Matches list who share DNA segments in common with each other, that they likely inherited from a common ancestor or ancestors, is a little bit trickier. Experienced genealogists can find these groups with a bit of effort:
1. Export shared DNA segment info for all DNA Matches.
2. Find the DNA Match you are interested in.
3. Look for additional DNA Matches with shared DNA segments at the same genomic location.
4. Compare those people in the One-to-Many Chromosome Browser.
If they triangulate you can repeat the process, adding an additional DNA Match each time, until you have identified a group of DNA Matches plus yourself (or a person whose DNA kit you manage) who all share a common DNA segment or segments, and are therefore likely all related through a common ancestor or ancestors who passed shared DNA to all of them. This is called a “cluster” of DNA Matches.
If the manual process described above is too laborious, we recommend that for the time being you work with known relatives and your closest DNA Matches, one or two at a time.
Another way to identify DNA Matches with triangulated segments is through the Review DNA Match page. On the Review DNA Match page, when reviewing shared DNA Matches, to the right of the estimated relationship you will find an indicator for DNA Matches who have triangulated segments both with you (or the person whose DNA kit you manage) and with a shared DNA Match. If there are no triangulated segments, the indicator will not appear.
On the desktop, you can hover over the indicator to see how many triangulated segments you (or the person whose DNA kit you manage), the DNA Match, and the Shared DNA Match all share with each other.
When you click on the indicator, you will be taken to the Chromosome Browser where you, the DNA Match you were reviewing, and the shared DNA Match that you both have in common will automatically be loaded as the comparison set.
This allows you to review triangulated segments quickly and efficiently, without guessing which matches will triangulate and loading them in the Chromosome Browser manually.
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