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).
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.
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.
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.)
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.
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.