How to Use DNA to Find Biological Family Connections

Are you looking for a way to use your unique DNA to find biological family connections?  You can use DNA testing to find people who you are related to, and in this post, I’ll tell you exactly how to do it. 

Below, you will find a comprehensive strategy that you can follow to help you find as much biological family as possible.

When I first thought about doing a DNA test, I was interested primarily in my ethnicity results.  Basically, I wanted that pie chart that you see on those DNA testing commercials. 

I had no idea that I would also receive DNA matches, which came in the form of a long, long list of people who I am related to!  Since beginning my DNA journey, I have found new close relatives, connected with cousins in other countries, and have seen close family members find biological family connections they have been longing for for decades.

How to choose a DNA testing company to find relatives

If you are interesting in taking a DNA test to find biological family, the first thing that you should think about is choosing a DNA testing company.  There are four major companies offering reliable DNA testing:

  • Ancestry DNA
  • Family Tree DNA
  • 23 and Me
  • My Heritage

There is a way to test with only two of the above companies, and transfer your DNA results to the other two companies on the list.  This way, you only buy two tests, but can have your DNA in all four databases – the absolute best way to make sure that you have the highest chance of finding the biological family connections that you are looking for.

If you have to choose just one company to test with, which would be completely understandable, then you should test with Ancestry DNA, and then once you get your results, transfer your DNA data to Family Tree DNA and My Heritage DNA.  It is a very easy process, so don’t worry about it being too technical.  What’s more is it is free to make the transfer, so you really only have to buy one test!

The reason that I recommend Ancestry DNA over 23 and Me is the size of the database.  Ancestry DNA has the largest database of DNA samples in the United States – much larger than 23 and Me, and so that is why I recommend testing with Ancestry if you can only do one company.

I don’t currently recommend any other DNA testing company that is not on the above list, but there are a few other places offering testing.  I can’t speak to the accuracy of the results, or the size of their database, however.

Note:  Even though I prefer Ancestry over 23 and Me, I should mention that many people have had success finding DNA matches there.  In fact, I recently found a previously unknown (to me) new close relative who had tested there a few years ago.  If I had tested there, too, I would have found her much earlier.

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Transfer your DNA data to as many other sites as possible

Once you do your DNA test and get your results back, you should begin learning about transferring your results to other places that accept DNA data transfers:

  • Family Tree DNA (if you didn’t test there)
  • My Heritage DNA (if you didn’t test there)
  • Gedmatch
  • Gedmatch Genesis

The idea is to make sure that your DNA is in all of the available databases so that you can make sure to find any biological family that has also done a DNA test.  It usually takes a few days to get your DNA matches when you upload them to another site, so that’s why I recommend doing this right away once you get your DNA test results back.

DNA matches are the key to connecting with biological family, but how are you related?

Once you have access to all of your DNA matches, the next step is to learn some strategies that will help you figure out how you and your DNA matches are related.  The first thing that you should know is that your DNA match will be listed with an estimated, or predicted relationship.  This estimation is based on the amount of shared DNA that you and your match have, and is only “correct” some of the time.

What does a second cousin match look like on Ancestry DNA

The image above is of one of my DNA matches, “Christopher”.  We share 249 centimorgans (cMs) of DNA.  All of the major testing companies will provide you with this type of information. 

I can use this number, 249 cMs, and compare it with known ranges of DNA.

A very dedicated genetic genealogist has put together an excellent shared DNA chart using statistics that he has been collecting.  Below, you can see the chart, and you can see that my match, Christopher, falls in the range of several different relationship types. 

He could be a half-first cousin once-removed, a second cousin, a great-niece or nephew, or any number of other relationships to me.

Blaine Bettinger Shared DNA Chart
Thank you to Blaine T. Bettinger for his hard work, and for sharing this image under the Creative Commons CC 4.0 license.

To figure out exactly who Christopher is, I will need to take a look at his family tree and compare it to mine.  By figuring out who our most recent common ancestor is, or who he or she likely is, I can then determine my exact relationship to Christopher.

How can I figure out how my match is related to me if they don’t have a family tree?

Since you know how much DNA you and your match share, and you have looked at the great chart above, you have a general idea of how you might be related to your match.  Still, you need more information to be sure.

If you are really puzzling over a DNA match, and they don’t have a family tree that you know of to view, you can use some other strategies to try to determine how you might be related, and at the very least, the side of the family that they fall on:

  • Take a peek at your shared matches or the matches that you share in common
  • Do a Google search for your matches username or full name.  Sometimes, you might find a family tree on another website this way.
  • Check the other websites where you have uploaded your DNA, since they might have their DNA there, too, with additional profile information or even a family tree
  • If they only have a small family tree, you might be able to find obituaries for their parents or grandparents, which often contain additional information about the family

Once you have a good idea about how you might be related to your match, you can consider moving on to the next step.

Consider contacting your DNA match

Once you know how you are related to your match, or at least you have a good ideas – or at least some idea, you could consider reaching out to your DNA match and letting them know what you have learned about your connection.

Contacting your DNA match can lead to so many great things, from brand-new close relationships to sharing old documents and photos.

Don’t forget to build your family tree as you explore your matches

As you go through your numerous DNA matches, you might realize that you are learning a lot about your family tree, so consider building your tree as you learn more.

You can read this post about how to use your DNA matches to build your tree “wide”, as I like to call it.


I hope that this post has helped give you a good idea about how you can use your DNA to find biological family connections.  If you have any questions or comments, or would like to share your experience, I would love to hear from you below.

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