14
Nov

How Can DNA Matches Help Build a Family Tree?

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While ethnicity estimates are fun and can occasionally reveal something previously unknown about our heritage, when it comes to building a family tree, our DNA match list is the most valuable tool that we have at our disposal.  You’ve heard all of the experts say that the best way to build a family tree is by using your DNA matches, but how, exactly, is it done?  In this post, I’ll explain exactly how your DNA matches can help you build your family tree.

Your closest DNA matches can provide information about your most recent ancestors

When people are first starting off with family tree research hoping to build an accurate biological family tree, even if they already know a lot about their family, I always recommend using information from the closest DNA matches to “verify” our most recent ancestry.  If we don’t have our grandparents and great-grandparents listed accurately in our family trees, then any research in generations further back might be flawed.

Basically, imagine that you are building a house.  The foundation must be stable, and each layer of bricks that you add to your house must add stability.  The same is true for building an amazing family tree.   Take a look at your closest DNA matches and answer – for your own research – the following questions:

  • How closely related are you to your top several matches?  It doesn’t matter if you know exactly who they are, but check out the number of centimorgans that you share and see the estimate relationship distance that you likely have.  Check out my post titled “The Beginner’s Guide to Shared Centimorgans” to learn how to find out how many centimorgans you share with your DNA matches.
  • Does the estimated relationship distance based on your shared centimorgans match both of your family trees?
  • If not, do you spot any of the same people in the trees of your “mystery” matches?
  • If you have lots of known close matches and everything looks as expected (i.e. your shared centimorgans fall within the expected range for known relationship), you can assume (pending any new information) that your most recent known ancestors are your biological ancestors.

Need help trying to figure out exactly how you are related to your DNA matches?  You might like my post titled, “How is your DNA match related?  Here’s a checklist.”

I always recommend that people keep a close eye on their DNA match list, and check back about once per month.  Every once in a while, we might get a relatively close DNA match that can help us learn more about our family tree, or help us get to know our close biological relatives.  I have personally been surprised by new DNA matches, and I’m glad I check my match list regularly.

Note:  If you do spot someone (or maybe more than just one someone) on your DNA match list that doesn’t seem to fit into your family tree, you’ll need more information before concluding that your tree is “wrong” or their tree is “wrong”.  I should also add that it’s easy to assume that our tree is the one that is right, and our DNA match is the one that has the “wrong” tree.  This is not always the case, and so we should be careful before making any decisions based on our theories.

Your 2nd-5th cousins and their family tree information can help you learn about your more distant ancestors

Once you feel confident about your immediate ancestors actually being your biological ancestors, you are ready to take a look at your more distant cousins.   When I say “more distant” I mean, specifically, your DNA matches that are estimated to be related to you at a second cousin distance to a fifth cousin distance.  These DNA matches are going to be very helpful for breaking past those pesky brick walls that we all have in our family tree.

By carefully examining as many of our more distant DNA matches as we can, we can find ancestors that we share in common.  Often, our DNA matches will have family trees that are more “complete” than ours, and might contain the name of a parent of our ancestor, or even a generation or two further back.  Furthermore, you might learn through the family tree of your DNA match who the siblings of your direct ancestor were (since your match will be descended from one of those siblings).

Using your DNA matches to build your family tree is slow work, and it doesn’t completely eliminate the need for traditional genealogy research.  In fact, the more I learn about my family tree through my DNA matches, the more helpful (and fascinating) I find traditional genealogy.  People in the genetic genealogy field prefer to say that DNA is a tool of the genealogist, not a substitute for genealogy.

Interested in advanced ways to use your DNA matches to build a tree and verify your ancestry?

One of the most amazing ways to use your DNA match lists, and information obtained from DNA matches, to build your family tree is to learn a DNA analysis strategy called “chromosome mapping”.  It sounds complicated, but there is a neat website that allows you to “paint” your chromosomes.  It’s called DNA Painter, and it’s free to use if you only want to paint your own chromosomes.  If you want to create multiple profiles and paint the chromosomes of family members (I do!), then you do have to subscribe.

What in the world am I talking about??  How does chromosome painting work?

  • To get started painting your chromosomes, you need to have access to a chromosome browser.  Chromosome browsers are provided on Family Tree DNA, My Heritage DNA, and on Gedmatch.  By comparing your DNA to the DNA of your match, you can figure out exactly which DNA segments you share, and where they are located on each chromosome.
  • It’s important to remember that even though we have 22 numbered chromosomes, we have two copies of each chromosome (one from our mother and one from our father).  This means that you should start out painting your closest matches with whom you share a known relationship.  Ideally, you also know if your closest matches are on your paternal or maternal lines in your family.
  • You can copy and paste your shared chromosome and segment information into your DNA Painter profile, and then actually be able to “see” which DNA segment you inherited from which recent ancestor.
  • As you paint in more distant matches with whom you know your relationship, you can identify smaller segments that you share with distant ancestors.

You could, in theory, use a spreadsheet to track DNA segment information, which is basically the “old school” method of DNA painting.  Whichever method works best for you is great!

But how can DNA Painting help you build your family tree?

By figuring out which DNA segments you inherited from a particular ancestor, you will then know which line of your tree you likely share with a DNA match.  You can then use my strategy of building a family tree for your DNA match (a Quick and Dirty tree works best) to figure out who your common ancestor is.  Occasionally, this might help you build your tree back one generation further, or assist you in the strategy of building your family tree “wide”, which basically means to add in relatives in your tree who are not your direct ancestors.

Conclusion

I hope that this post gave you some ideas as to how your DNA matches can help you build your family tree back more generations and more completely.  If you have any questions about something that you read in this post, or you would like to share your experience using information from your DNA matches to build out your family tree, I would love to hear from you in the comments.

Thank you for stopping by today 🙂

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How Can DNA Matches Help Build a Family Tree?
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How Can DNA Matches Help Build a Family Tree?
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You've heard all of the experts say that the best way to build a family tree is by using your DNA matches, but how, exactly, is it done? In this post, I'll explain exactly how your DNA matches can help you build your family tree.
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Who Are You Made Of
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