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How to Make a Mirror Tree on Ancestry

In this post, you will learn what a mirror tree is, the basics of how to make a mirror tree on Ancestry, and what it can do for you in your search for family.

Building a mirror tree can be an excellent way to help determine who your biological parents, grandparents, or great-grandparents were.  The power of the mirror tree comes from Ancestry’s vast database of millions of DNA tests and public member trees attached to those DNA results. 

Update: This post was written before the helpful new feature on Ancestry DNA called “ThruLines”. The ThruLines feature can be used to explore your ancestry in a similar way as described in this post.

What is a mirror tree?

A mirror tree is a “mirror image” of an entire tree, or a certain line, of a tree of one of your DNA matches.  If the mirror tree is attached to your DNA. Ancestry DNA’s software can analyze the family trees and DNA results of your DNA matches and provide you with “Shared Ancestor Hints”. 

How does a mirror tree help identify ancestors?

It sounds kind of magical, doesn’t it?  A tree that can help you figure out a family mystery – and it has a cool name, too.  While it definitely isn’t magic, building a mirror tree can be a very helpful strategy in helping you figure out which family your mystery ancestor descended from.

Shared Ancestor Hints are the “magic” that can give you a good idea as to whether you’ve included the right people in your mirror tree.

The idea is that if you build a mirror tree using the tree of a relatively close cousin as a match, and you end up getting several Shared Ancestor Hints on a particular line of the mirror tree, it means that you have other DNA matches who have that person in their tree. 

The implication of this is that all of you could potentially share this common ancestor.  If you know nothing about your family tree, you can then work on the assumption that you are descended from that person (or couple).

For example, let’s pretend that you have a first cousin match show up on Ancestry DNA.  Full first cousins share two out of four grandparents.  If you are lucky and your first cousin has a family tree that includes their parents and grandparents, you can build a mirror tree using their information. 

If you build the tree out a few more generations, using the information from your cousins tree as a “base”, you should quickly begin to get Shared Ancestor Hints on one side of the tree.  You will then know, almost beyond a doubt, which couple in your cousin’s tree are your grandparents. 

All you would need to do then is figure out who the children of the grandparents are in order to figure out who might be your biological parent.

So how do you make a mirror tree on Ancestry?

Step One

The first thing that you will need to do is pick the person whose tree you will use as a guide for your mirror tree.  Using a first, second, or third cousin match is the best idea, if you have a match of that type and they have a tree where their parents, grandparents, and great-grandparents are listed.

Note:  If you have a few first-third cousin matches with the same couple in their tree, you don’t need to build a mirror tree.  You should assume, at least for now, that you are descended from that couple in some way, and you can use other types of research to figure out exactly how. 

If you still decide that you want to build a tree using this couple, the benefit could be in just collecting additional “proof” in the form of Shared Ancestor Hints from other DNA matches, basically saying that you have matches that descend from ancestors of that couple that you share in common with your close matches.

Step Two

Start a brand-new family tree on Ancestry.  (Click here to learn how to build a tree on Ancestry).   Enter yourself as the main person, and then enter the couple who you think you might be descended from as your parents. 

If you have a first cousin match and you don’t know which side of the family you are related to, then enter their parents as your parents, and their grandparents as your grandparents, etc.  If you have a second or third cousin match, you just have to pick a couple who you think you might be related to, and enter them as your parents.

Step Three

“Build out” their family tree as many generations as you can (at least 3-5, if possible).  What I mean by “building out” is adding generations further back in the tree, using more traditional genealogical methods. 

Ancestry makes this easy, since you will get tree hints (different than Shared Ancestor Hints) for the people in the tree, and you should be able to use this information to figure out the tree a little further back. 

The further back you can get, the better, since building the tree more generations back means that there are more potential descendants that might have them in their tree – meaning a better chance of Shared Ancestor Hints.

Step Four

Attach your DNA to your family tree, and choose yourself in the tree as the main person.  (If you need help, you can read my post about how to attach your DNA to your tree on Ancestry).  You might have to wait up to a few days for Shared Ancestor Hints to populate, but sometimes it only takes a few hours.

Step Five

Check your Shared Ancestor Hints.  If you have some, they will show up on your main DNA Insights screen (image below):

Shared Ancestor Hints and a Mirror Tree

There are a couple things that you will need to be careful about as far as Shared Ancestor Hints are concerned.  First, you will always get a Shared Ancestor Hint for the person whose tree that you used as a guide for your mirror tree. 

You have to ignore this hint, since it doesn’t mean anything – it only appeared because you intentionally made a tree with those people as your ancestors.

The other thing that you really need to be careful about when making a mirror tree is if the person whose tree that you used has siblings or very close relatives who have also done the test and have those people in their tree.  This can “skew” the results in favor of the people who you put in your mirror tree. 

If you get several hints, check through the trees of the people who show up as having shared hints with you, and make sure that they are not all from the exact same family.

Step Six

Once you’ve checked to make sure that your Shared Ancestor Hints are valid, and if you got several, you might have cracked a brick wall in your family tree!  Congratulations! 

You have a lot of hard work ahead of you, though, since depending how far back in your tree the couple that you chose as your parents is, you might have a few generations of family to research and figure out the exact person who should be in your tree.

For example, let’s say you made a mirror tree with John Smith and Anna Clark as your parents.  You didn’t get any Shared Ancestor Hints for Anna Clark’s side of the family, which is great, since it helps you eliminate that line as a potential match for your tree. 

You didn’t get any Shared ancestor Hints for John Smith, but you did get a few for his parents, Gabriel Smith and Sarah Higgins.  This means that you are descended from Gabriel Smith and Sarah Higgins.  You might also be descended from John Smith, too, but your mirror tree doesn’t prove that.

Now, you’ll need to research all of the children of Gabriel Smith and Sarah Higgins.  Don’t feel too hopeless, since you’ve pretty much determined a line in your family tree! 

Learn as much as you can about the children, grandchildren and great-grandchildren of your ancestors.  If you find that one of their children, or grandchildren, married a person with a surname that you’ve seen a few times pop up in someone else’s tree, you can then build a brand-new mirror tree with that couple as your parents (repeat this whole process, attach your DNA to the new mirror tree).

If you get Shared Ancestor Hints on both sides of the family, then it’s possible that you have found the “right” couple, and they might be the descendants of Gabriel and Sarah that you are descended from, too.

Does this make sense?  Don’t worry if it seems confusing, once you build your first mirror tree, it will make more sense to you.  You are always welcome to ask me questions, as well.

Do you need an Ancestry subscription to build a mirror tree?

You don’t need to have a subscription to Ancestry to build a mirror tree, per se.  In fact, you can build as many mirror trees (or family trees) as you want, no subscription required. 

Without a subscription, assuming that your mirror tree is set to public, you will be able to see if you have “Shared Ancestor Hints” with anyone else in your DNA match list, which is amazing when you are building a mirror tree.

In order to see who the Shared Ancestor Hints are, and to access the family trees of your matches, however, you will need to have an Ancestry subscription. 

If you want to try out the mirror tree method, and need a free trial to see if it will work for you, you can click on this link (I do get a small commission if you end up subscribing at the end of your free trial, at no extra cost to you) Ancestry Free Trial

What if you don’t have a really close match, can you still build a mirror tree?

If you don’t have a first, second, or third cousin match, you can still build a mirror tree. 

You will have to be a little more dedicated to building multiple trees, figuring out common ancestors and who married who, keeping track of geographic locations, etc.  With enough time, mirror trees with only fourth cousin matches can still work for you. 

I’m planning on putting together a more extensive post on this topic, since I’ve been working with an adoptee who is in this exact situation, and I would like to share what I’ve learned with my readers.


I hope that this post served as a good introduction to the concept of mirror trees, how to make a mirror tree on Ancestry, and that you learned enough to go out there and make a few mirror trees of your own. 

If you have any questions about anything that you read here, or if you want to share your story about mirror trees, I would love to hear from you in the comments.

Thanks for stopping by!

Share the knowledge!

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Marilyn Keck

Sunday 15th of October 2023

How do I get all of my ancestry on a CD?

Marilyn Keck

Sunday 15th of October 2023

How can I get all of my ancestry on a CD?

Fay Marsh

Friday 27th of August 2021

Hi, thank you for this info……. Just wondering though……. I have just built a mirror tree putting in the “other” person’s family line for several generations and then adding my own family line back to the generation where I THINK we both intersect. Should I attach my DNA to myself or the “Home” person from the tree I’ve just made a mirror copy from. Thank you in anticipation of a reply. Cheers, Fay


Monday 13th of April 2020

Hi Mercedes. I am adopted and my birth-mother gave me the name of a man who she says is my birth father. His children will not do a dna test. Can I do a mirror tree with me as the home person and him and his wife as my parents? Basically mimicking one of his children? I have researched his family tree and nothing has pointed me in his direction at all (unless he is adopted as well!) Please let me know what you think


Tuesday 21st of April 2020

Hi Elliell, If you decided to do a mirror tree, building a tree with you as the home person and him as your father and leaving your mother blank (or adding his wife, if you want to), you should get common ancestor hints in your Ancestry DNA results. While it's not a guaranteed way to determine if he is your biological father, you can get a good idea as to whether you share recent common ancestors with this person - a good clue that points you in the right direction.

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