Identifying branch points with your DNA matches can be a useful strategy in your DNA research. Understand what branch points are and how you can use them with your matches.
Determining how you are related to the significant number of DNA matches you have on different testing sites can be overwhelming. You may not understand at first how certain matches are related to you, but an often overlooked principle in figuring this out has to do with understanding some simple principles of DNA inheritance.
What are branch points?
Branch points are any location on a family tree where an individual or couple had more than one child. The inheritance principle is that any two people who have descended from a common ancestor should have inherited a somewhat predictable amount of DNA. Therefore, if you know their branch point, you should be able to predict the amount of DNA they share. And the reverse is true, if you know the amount of DNA they share, then you can predict their branch point.
Importantly, if two DNA matches are sharing the “right” amount of DNA according to their genealogy relationship, that DNA “verifies” their connection to each other, and helps solidify that ancestor, or ancestral couple’s, place in that family tree.
Another good DNA inheritance principle that comes into play when we talk about Branch Points, is the fact that we are more confident in our DNA relationships when the ancestral connection is closer. For example, it is much easier to identify a first cousin who shares 850 cM than it is to determine if someone sharing 30 cM is your third or fourth cousin.
This Branch Point principle has two main applications in our genealogy research:
- VERIFY your own family tree.
- CONNECT you to your match’s family tree. We call this your generation of connection.
Think of branch points in the terms of a tree. This is where the ancestors “branch off” from each other.
One relatively quick (but not fool-proof way) to see the branch points in your own tree that have a DNA component is to check the ThruLines tool from Ancestry DNA or the Theory of Family Relativity from MyHeritage DNA. These tools are meant to show you how individuals on your DNA match list could fit into your family tree. By comparing their genetic relationships (measured in centimorgans) and their genealogy relationships (like 1C, 2C1R, etc) you can determine if specific branches of your tree are verified.
Now, be careful, as when the genetic and genealogy relationships are verified, it just means that two people likely connect at that generation. It doesn’t guarantee that you have the right name in that slot.
Identifying branch points is a strategy that you may already be doing, you just didn’t have a word for it– now you do! If you haven’t been using branch points in your genetic genealogy research, now is your chance. Want to do more with your matches? Check out our free guide to learn about four next steps you can take for finding unknown ancestors using your DNA.
