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Build a Family Tree for Your DNA Match to Figure Out Your Connection

The best way to figure out how you are related to a DNA match is to build a basic family tree for them back to your common ancestor. In this post, learn why this works and how to do it.

I know that this sounds like a crazy idea.  You have enough work on your hands trying to build your own family tree, so why should you spend any time at all trying to find other people’s ancestors? 

Believe it or not, this is a very useful strategy for family tree research, even though it might seem counter-intuitive.  In this post, I will explain how to build a quick family tree for your match, and how this can help you figure out how you are related.

Build a Family Tree for Your DNA Match to Figure Out Your Connection

How to build a quick and dirty tree for a DNA match

Instead of calling it a quick and dirty tree, some people prefer the term “skeleton tree”, or a “bare-bones” tree.  The idea is the same, though.  Building a simple family tree, with only basic information included about direct ancestors is what we are trying to achieve.

The following steps are exactly the steps that I take when I am doing this for my DNA matches.  I’ll walk you through the entire process, from choosing which matches to do this with, to what to do with the information once you’ve figured it out.

It’s not very hard – so don’t worry!  It’s also a great way to hone your genealogy skills.

I always use Ancestry to create my family trees.  It’s super fast and easy, and if you have a subscription, you can add people and search through records very easily. 

You don’t need a subscription to build your tree, and you can make as many trees as you want.  If you want to search through records and family trees, however, a subscription is required.

Click here to buy the Understand Your DNA Results Ebook

Choose the DNA match that you are going to work on

This strategy is best used with DNA matches that have a family tree that includes at least the names of their parents.  It’s easier if you can find DNA matches that have their grandparents listed in their family tree, too.

DNA matches that are best for this strategy:

  • Have parents and hopefully grandparents in their small tree
  • Have parents and grandparents that were born in the United States
  • Are related to you at approximately a fourth cousin distance or closer

It doesn’t matter where you find your DNA match – you can build your quick and dirty tree on any platform.  In fact, you could even build the tree in a notebook. 

As I mentioned before, I always use Ancestry, but it is not required.

Figure out the full names of your DNA match’s grandparents

Many people with small trees have their parents listed, which many times will show up as private.  They may or may not have complete information listed about their grandparents. 

It can be a little bit tricky to figure out exactly who your matches grandparents were, but here are some tips:

  • Online obituaries are an amazing source of information for this.  Simply do a Google search for the full name and add “obituary” to the search term.  You might find an obituary for the parent or grandparent of your match, or even one for one generation further back.  Often, you might find names of living siblings, etc, which are useful to help you identify the family a generation further back when you are looking through census records.
  • Other online family trees are very helpful for finding clues, especially if the people in your match’s tree were born in the early 1900s – there is a good chance that they have a good number of descendants or other cousins who have included them in their trees.
  • If your match’s recent ancestors were born in the early 1900s, you might be able to just skip to the next step – locating their family in the 1940 Federal Census.

Locate their grandparents in the 1940 Federal Census

Most people who are doing autosomal DNA testing today are old enough to have grandparents born before 1940, which means that you can often find your DNA match’s grandparents on the 1940 Federal Census.  The key is to make sure that you have found the correct person on the census, so you’ll need to make sure that you have accurate information so you can make sure that what you find matches up with the person you are looking for.

For example, if I am trying to find my DNA match’s grandfather on the 1940 census, and I know his name is Joe Pointer, and he was born in Newark, NJ in 1930 (information I learned from his obituary), I will take the following points into consideration:

  • I need to look for a ten-year old Joe Pointer in the 1940 Federal Census
  • I’ll make sure that he was born in New Jersey
  • I may or may not already know the names of his grandparents or siblings (from his obituary or someone else’s family tree), so I’ll make sure that those names match up
  • I’ll make sure to make a note of who his great-grandparents were, were they were born, and whether or not they are living with other family members that can help me build the tree one generation further back.

It’s important to make sure I get the basic information about the great-grandparents correct (years of birth, places of birth, etc) since I will need this to make sure that I am able to locate the right family in the earlier census records.

Try to find their great-grandparents in the 1900-1930 Federal Census records

If I am able to find the names of the great-grandparents in the 1940 census, I might be feeling pretty confident and ready to try to locate the great-great grandparents.  It would be am mistake to skip looking for my match’s great-grandparents in the 1930 and 1920 census years. 

This is because there is a great deal of information on these records, and if I take the time to look for the same family, I’ll learn something new each time that can help me be more confident about who the parents of the great-grandparents might be.

Naturally, I will make sure I take note of any clue that will help me locate the same people while they were younger and living with their parents (my match’s great-great grandparents).

Locate their great-great grandparents on earlier census records, or in other family trees

By this time, I know the names of the great-great grandparents on at least one line.  I might be able to determine that I am not related through this line, and I can start working on another line of their tree. 

If I am not sure, I’ll keep working and try to find the great-great grandparents on earlier census records.  Census records are always helpful, but they include a lot of information starting at about 1870, so there is plenty of opportunity to locate great-great grandparents.

If you have followed my tips so far, you already know how to make sure you have spotted the right family (i.e. birth years and other family members should line up, etc).  Once you add the great-great grandparents onto your tree, there is a good chance that other descendants of these individuals have added a public family tree to Ancestry (or somewhere else) and you might be able to to learn even more about the families through those trees.

Isolate the family lines where you think your connection might be, and find their great-great-great grandparents on those lines – if necessary

So, as you are building the family tree for your match, you might stumble upon a line of their family that seems very likely to connect to yours, so you can focus on it.  Alternatively, you might know that you are connected to your match on your Dutch side, and so you can ignore the Polish side of your match’s tree. 

Your time is valuable, so any sort of deduction that you can make will save you time so you can focus your efforts on the branches of your match’s tree that will help you learn the most about your family.

If you followed my advice and are building a tree for a fourth cousin match or closer, there is a good chance that if you add all of the great-great grandparents to your match’s tree, you might spot a surname that is familiar to you and are close to finding your connection.  If you still don’t recognize names, you might need to go one or two generations further back to find your relationship.

Compare what you have learned with other public family trees online

Once you think you know how you are related, you can compare what you have learned with other public family trees online.  I like using Ancestry for this, since they have millions of family trees and you have a good chance of finding the person who you are looking for on that site.

Don’t forget to add this new connection, along with their ancestors who are connected to you, to your family tree

Once you figure out your connection, make sure to add everyone in to your family tree.  Start from your most recent common ancestor, and move forward, adding all of the information in that you learned about your ancestor and their other descendants.  This will help you identify other DNA matches more quickly in the future.

Should you contact your match?

Sometimes I do contact my match, and sometimes I don’t.  I definitely don’t say “Hi, I built a family tree for you”, since I don’t want to sound too weird- ha!  I might say something like, “I think you are descended from the granddaughter of my great-great grandfather, so and so”. 

People are usually very happy to learn more about their ancestors – many times they stop building their trees because they get stuck.  They might be very happy that you gave them a hand past their brick wall.


I hope that this post has helped give you some ideas as to why building a small family tree for someone else is actually a very good use of your time.  If you have any questions, or would like to add something that you think would help out other readers, I would love to hear from you below.

Thanks for stopping by!

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Jim Ward

Sunday 4th of February 2024

I'm going to try this with an IBC match who can't find a common ancestor. We match on the same chromosome locations and so does her late mother. Even more interesting is that she's Australian - 2 of my great grandfather's brothers emigrated from Canada and I have some AU cousins, 2 of who I have met. But the IBC match is bugging me.

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