“Pruning” to Find Shared Ancestors in Private Trees

If you have taken the AncestryDNA test and “attached” a family tree to your results, Ancestry’s computers will search the trees attached to your DNA matches and let you know when it finds the same direct ancestor(s) in both trees.  A leaf icon will appear beside the green VIEW MATCH button indicating that there is a so-called Shared Ancestor Hint (SAH).

The small green leaf icon indicates that this match has at least one Shared Ancestor Hint.


If the match’s tree is public, when you click the VIEW MATCH button, the next screen will show you who the shared ancestor (or couple) is, with lines of descent to both you and your match. Sometimes, there’s more than one connection.  The example below is the first of five different SAHs to this match, “D”. I can toggle through them using the grey arrows.

Lines of descent connecting me and “D”, a 3rd cousin twice removed (3C2R) through our shared ancestors, Bernard Migues (also spelled Miguez) and Leocadie Etié.


But what can you do when you get a SAH to a private tree? Of course, first, I would message them and politely ask if they’ll tell me who the shared ancestors are. If that doesn’t work, I can sometimes get some insight into which side of your tree the connection is on using the Shared Matches tool.  For example, if the person in question is a shared match with a maternal aunt but not a paternal first cousin, I can probably safely assume that the connection is on my mother’s side. Another trick is to use the Search Matches tool (the blue button at the top of your match list) to look for specific surnames in my tree.  If the match with the private tree pops up, I may be able to figure out where the link is.

Another trick that I use when I want to know who the shared ancestors are in a private tree is one I call “pruning”. Briefly, I systematically prune one branch then another from my tree and track whether the SAH persists or disappears.

First, I remove the relationship between myself and my mother in my tree. To do this, I go to my profile, click the Edit button at the top right, go to Edit Relationships, and click the blue X beside my mom to remove the connection.

Use “Edit Relationships” to selectively prune a branch from your tree.


This doesn’t delete her record from my tree, it just makes her not-my-mom for a while. (I always start with my mom, because about 90% of my DNA matches are through her. You may want to start with your father, depending on what you know about your own tree and DNA relatives.)

My tree, pruned to test for Shared Ancestor Hints through my father’s side.


Next, I detach my DNA from my tree, wait for all of the SAHs to clear, then reattach it.  This step is not absolutely necessary—and Ancestry customer support advises against it—but I like to know when the SAHs have “reset”, and DNA geeks sometimes have to go renegade.


Once the SAHs have repopulated, I check to see whether the match with the private tree still has a leaf icon indicating a SAH. If they do, I can be pretty sure the connection is on my paternal side; if they don’t, it’s on my maternal side. I always confirm by reattaching my mother, detaching my father, and repeating the steps described above. If the hint disappears when I prune my mom’s branch and reappears when I regraft it, the connection is maternal. Conversely, if it disappears when I prune my father and reappears when I reattach him, the connection is paternal. If the leaf icon persists for both parents, there is a connection through both of them.

Let’s pretend the connection I’m interested in is through my mother.  I would then do the same thing with her parents:  first prune her mother, then her father, and see how the SAH behaves. If this step narrows down the connection to, say, my grandfather, I move on to his parents and repeat the process.

Recall the SAH example to a known cousin, “D”, that I showed above.  We share the ancestors was Bernard Migues and Leocadie Etié. Imagine instead that her tree had been private, and I had to use pruning to identify them as the SAH. The screenshot below shows what the pruned tree would look like, with Bernard and Leocadie circled in red.

A tree pruned to identify the shared ancestors in a private tree. In this hypothetical example, the connection is through Bernard Migues and Leocadie Etié (circled in red).


Of course, if I were doing this with a tree that was private, I wouldn’t yet know that Bernard and Leocadie were the shared ancestors.  I would continue pruning, first one parent then the other of Bernard, then the same for Leocadie. But something interesting would happen: the leaf icon wouldn’t disappear. Not when I pruned Bernard Migues Sr., nor Marie Bernarda Romero, nor Pierre Guillaume Etié, nor Victoria Borel, nor all four of them at the same time. That would tell me that Bernard Migues Jr. and Leocadie Etié are direct ancestors in the private tree. That is, they are my shared ancestors with the DNA match!


Some pointers and cautions

Pointer:  Notice in the pruned tree above that I replaced the “missing” parent with a note to myself to reattach the ancestor.  That’s makes rebuilding the tree quick work, even if I forget a name. Make sure the note to yourself is different enough from the real name that Ancestry’s computers won’t mistake it for a real name.

Caution:  Recall that “D”, my 3C2R, had five shared ancestor hints, because she is related to me five different ways. (There’s at least one more connection that isn’t in “D’s” tree yet. Ai-yi-yi, Cajuns!) When that happens, there will be points in your tree where you get the leaf icon through both parents of that ancestor. The way to tell those points from the “Aha! I found the shared ancestors!” point is that when you remove all of the parents, the leaf icon disappears. You will have to track down the shared ancestors on one branch, then go back and track down the other shared ancestors on the other branch. If there’s enough interest, I can write up an example of multiple SAH.

50 thoughts on ““Pruning” to Find Shared Ancestors in Private Trees”

  1. I do a surname search and the matches with private trees show up and then I record the surnames in the notes box.

  2. Hi. Good article. I had already figured out how to use Shared Matches and Search Matches to help determine how I am related to people with private trees. But I never thought of the “pruning” technique. I’m wondering when you detach, say, your mother from your tree, how long does it take for the system to repopulate the leaf hints?

    1. That’s a good question, and the answer is: it depends. Sometimes it happens quickly (30 min or do), sometimes it can take a day or more. When it resets quickly, I take advantage and do a lot of pruning steps that day.

      1. Thanks. One more thing to look for: I had a match with a person who has a private tree. Our shared matches pointed to a particular ancestor I had as our common ancestor. When I messaged this match and had no response, I noticed that my match had saved an image to their private tree that I had uploaded. This image was on the profile of the ancestor I had assumed to be our common ancestor. 🙂

  3. Neat trick but I’m wondering how long it takes for the shared ancestor hints to repopulate?

    1. Caution – if you have a very large tree (30,000+ individuals), the update occurs over time and in my experience has taken up to THREE WEEKS. One workaround for this is to build a second tree with only direct ancestors (no brothers or sisters, etc.). Attach the DNA account to the new tree and proceed to test per this article.

        1. I’m not sure why, but I can’t seem to comment directly, only ‘reply’. My question is: When you say that unattaching and re-attaching your DNA is optional, is that correct? I ‘pruned’ a branch two days ago and haven’t seen any change yet. Still 23 SAH’s as always. Do I really need to unattach the DNA and re-attach it to get the SAH’s to kick back in? If not, I’ll be patient!

        2. Yes, unattaching/reattaching is optional, but it puts you in the situation you’re in now, where you don’t quite know whether the new hints just haven’t kicked in, or whether pruning this branch didn’t make a difference. That’s why I always detach/reattach, so I know for sure.

        3. Thanks. In this case, though, I’m certain at least 5 SAH’s are from the maternal side, and that’s the side I ‘pruned off’. There is no overlap between the maternal and paternal that I’ve ever found, they both emigrated to the US from different countries. I expected those 5 to drop.

          So when you say you ‘detach’ – I’m not seeing that option. Do I need to attach it to some other tree in the mean time? ‘Change’ is the only option I’m seeing. Thanks!

  4. Wow thats a lot of work. You demean yourself , though,when you use the word trick. Another suggestion – operation-move-decision- ……..

  5. I’ve never tried “pruning” so that will be an interesting experiment with one particular very close match on my father’s side.

    What I also do is when using Search Matches for another purpose, if I happen to see a private tree match (with or without a SAH) come up on the list for that surname or that location, I add it to the notes for that match. It may come in handy later.

  6. I am curious what is the timing between detachment when pruning and when the leaf shows up ? Is it mere minutes, hours or days ? I love the way you think !

  7. So ingenious I can’t understand why others haven’t thought of this before! I am trying it now but have a question/comment or two . . .

    1. Although I eventually found the “edit relationship” button, it took me a while because there are so many edit buttons scattered around. You said that you went to your “profile” and there are even a couple of those, depending on where your mindset happens to be. You might consider clarifying that you mean the profile asssociated with your name on the graphic presentation of the tree.

    2. When I removed my mother as my mother she remained as my father’s spouse until I reloaded the tree and I was the son of an unknown spouse . . . a bit confusing. In fact, if I use the vertical tree rather than the horizontal tree that you use, that is still the case. Only when I switch to the horizontal tree does she completely “disappear” . . .

    3. How long does it take before the hints are reset? Mine remain untouched at the moment, even for those with whom I have a known maternal relationship (e.g., a maternal aunt). I’ve tried reloading the page, etc., with no effect.

    Thanks again – This will be useful!

    1. I’ll try to improve the directions when I have wifi. The hints will reset in anywhere from 30 min to a day or more. Varies widely.

  8. Sometimes you can luck out and search a suspected ancestor and you can find the ‘locked’ tree in the Private Tree list, meaning, your match hasn’t hit the unsearchable button.

  9. I presume this works because those private trees were indexed. Some private tree owners check a particular box to keep them out of the index.

  10. Three example you provide are also my direct ancestors! I.an a descendant of Bernard George Miguez and Leocadie Etier, on my father’s side. In fact, I am a descendant of Amelina Miguez! I haven’t done DNA testing yet, but got interested in the state of the art because my mother did her DNA last year. I’d like to know more about where you fit in the Miguez family tree.

      1. I should know better than to type on my phone, especially late at night. I hope you can make sense of my message above, with all its errors.

  11. My friend has been using a methodology like this for a long time, even without DNA. She makes a hypothesis, perhaps that “his father’s name is John” and puts that in. She then looks at the hints she gets and the matches to trees where the father’s name is John and sometimes there is enough data to prove her hypothesis. It really looks like magic when she’s doing it.

  12. Hi Leah,
    Thanks for the very good informative OP. My wife who is way more the genetic genealogist is our family than I am has been trying to do something similar on FTDNA, but I don’t think family trees on that site are as flexible or robust as those on AncesryDNA. She also comes from a very endogamous heritage.

    At FTDNA the “hints” she uses are really shared segments viewed in the chromosome browser using various cM thresholds (depending how fine grained she chooses to be at the time). She then downloads and does her pruning thru Excel.


  13. I have only 2 shared ancestor hints on my tree of 3500 individuals. in Ancestry DNA i have 1300 plus possible matches, 3 of whom we have identified a shared ancestor.

    My question is can this be used to narrow down possible links to ancestors. I have many dna strong matches to people who are adopted and looking for family.

    On my shared matches I see three in particular over and over. Each has no tree linked online nor have they come up under surname searches.

    i was wondering if “pruning” would at least give me a hint what side of the family to begin looking on?

    Also do most people have both a vertical and a horizontal tree online? mine is only vertical at this time. I can see the benefits of both. also of separating Mom’s line, dad’s line and my wife’s line.

    1. Pruning will only work if you have Shared Ancestor Hints to another tree. Since adoptees who are searching don’t know their family trees yet, you can’t use it from your end to find the connection.

      However, an adoptee can combine a trick called “mirroring” with pruning. There are good instructions for mirroring in the Files section of the DNA Detectives Facebook group (https://www.facebook.com/groups/DNADetectives/).

      As for trees, there are different ways to do it. I have a large private tree that includes many lineages and a direct-ancestry-only tree that I have attached to my DNA results.

      1. I tried the pruning by removing Mom and both shared ancestor hints disappeared. In both cases the SAH was for a specific Individual who is in my tree but not the other two trees.

        1. OK, I must be doing something wrong. I started with 23 SAH’s on my husband’s tree. I then ‘pruned’ off his grandfather’s branch. I did this by going to his father’s profile and deleting the link to HIS father. I then attached the DNA to a fake tree, waited until the SAH’s went to 0, and re-attached it. An hour later, I have 19 instead of 23 SAH’s. OK, that looks promising. I click on the SAH’s and the first one is for the OTHER side of the family. The side I pruned off. It shows a leaf, but when I open it, it doesn’t show the connection, as if there is no SAH. So why is it still listed…? Now I’m not sure I can rely on whether someone still shows in the count of SAH’s or shows a leaf.

          I posted my question on the Ancestry.com facebook group to see if anyone can figure it out as well.

          Your thoughts are appreciated!

        2. Sounds like you did everything right and that their system is glitching. That happens sometimes, and all you can do is wait it out. The Ancestry Facebook group will tell you not to do what you just did — remember, we went renegade — so just ignore them. Try again in a few days.

    2. I think what you mean by vertical and horizontal trees are really just two different views of the same tree. There are two green buttons on the left side that you toggle between.

  14. A second related question is how do people download their DNA matches to a spreadsheet. i am looking for a link to do that as it seems to be the easiest way to discover who has fallen off when I unhook a relationship.

    1. Your matches will still be your matches, regardless of how your tree changes. The pruning trick only affects whether you get a Shared Ancestor Hint.

  15. My question is, so what? What do shared ancestor hints gain you, in your genealogy research? If I already have that person in my tree, then I have already researched that. I suppose you could look at it as genetic confirmation of your research, but we all know it is not proof that that is the source of the DNA connection. When I see a shared ancestor hint, what I want to know is, what chromosome is this on, and what segment? If I can build up enough identified segments, then I have a map which may lead me to new discoveries. Without knowing the Chromosome and segment, this is just a curiosity, “Hey we are related, isn’t that cool.” sort of thing. What am I missing here?

    1. I don’t use pruning very often, as I usually get a response by simply asking who the shared ancestors are. It’s just another tool in the toolbox. I primarily use it for unknown parentage cases, when I need to use the trees of matches to figure out who the ancestors are. For my own matches, I sometimes use it so I can tailor my message to the DNA match. For example, I have a 2C1R with a locked tree. She logs in regularly but wasn’t responding to messages. Shared Matches weren’t helpful in narrowing it down, because we’re Cajun. I used pruning to figure out how she is related to me, then sent her a message with the names of our shared ancestors to pique her curiosity. She did respond that time, and I was able to send her some pictures of her grandmother and my great grandmother that she had never seen.

    2. I keep reading articles and a good book and still can’t really understand how to use the matches. You say that the shared ancestor is not proof that is where the DNA connection lies. My biggest problem right now is finding evidence that my grandmother’s father was really her biological father since she was born a couple of years before the marriage. Unfortunately it is in the line I’ve researched, found the most information and stories, and traced the furthest back.

      I just recently realized my connection may not be biological. I get few close matches and most without trees. I’ve uploaded my DNA and Tree to all the sites I know about (and can’t figure out yet how to use them). I think I’ve seen tools to find out the chromosome and segment of matches, but still can’t figure out how to use them. Even if I do, is there any way to prove biological relationship to an ancestor?

      My brother and I (I manage his DNA results) are the oldest in our family line. I have one maternal cousin I can ask to take the DNA test if I send her a kit. Just waiting until it goes on sale again. But if doesn’t give evidence of biological relationship to an ancestor, I’m not sure I want to spend the money.

      Any advice would be gratefully appreciated!

      1. Did the supposed great grandfather have any other children whose descendants would consider testing? If not, do any of his siblings have living descendants?

        1. Yes, there were other children. But I have no contact with the family or even my grandparent’s families except the cousin. I do need to check and make sure I’ve found all the info I can on the descendants of the siblings as far as I can go. I think so but haven’t checked in awhile.

          Any trees I could find them on would have them marked private I don’t know how to find out who they are.

        2. You may have to find the living descendants and ask them to test. Once you get past the 1940 census, you’ll have to rely on BMD records, city/phone directories, and obituaries. I *love* obituaries. Sometimes people list relationships in their Facebook profiles. And then there are databases like BeenVerified that have contact info and connections.

        3. There was no reply button on your last message so I’ll use this one. Thank you so much for giving me your ideas. I have tried some obituary searches without very little found. But when I get back to Ancestry (No chance to do it today) and check for descendants of his other children I’ll try searching for obits for them. I checked sites like BeenVerified and they have many more negative reviews than positive. TruthFinder was better, but one site had mostly negatives for them.

          Then I found out all the sites I checked didn’t look for Canadians and that’s where all those descendants are likely to be. I looked for Canadian people finders and will check those out.

  16. I found that I had to clear my browser data before the shared ancestor hints refreshed. Just refreshing the screen didn’t do it for me.

  17. It doesn’t seem as though my last message to your reply got posted, but it won’t let me post it again.

    Didn’t want you to think I wasn’t greatful! Hopefully this will post.

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