Do You Have a Suspicious Branch in Your Tree?

A Segment-ology TIDBIT

Although this Segment-ology blog is focused mainly on understanding and using DNA segments, I’ve also tried to look at the genealogy part of the genetic genealogy equation. We need both genealogy and DNA tools. AncestryDNA has some good genealogy tools that help us with our DNA Matches.

One of the powerful tools is ThruLines. Ancestry uses this tool to analyze your Tree, each Match’s Tree, and every other Tree in its inventory to try to build links to a Common Ancestor (CA) for you and each Match. This includes finding CAs with private, but searchable Trees, and with small Trees that may have only a Match’s parent or grandparent. In all cases Ancestry will try to fill in any gaps between the CA and you and/or your Match. The result is a diagram showing how you and the Match are related through a CA, along with reference material to indicate how they determined any generations they used to fill in a gap. This is a powerful tool, which can be used in a variety of ways.

I’ve written about:

  • How ThruLines Works, here.
  • Helping ThruLines help you, here.
  • ThruLines Xray vision (into private Trees), here.
  • Adding ThruLines info into Match Notes, here.
  • Using ThruLines and Shared Matches to form Clusters, here.
  • Using ThruLines to Extend the MRCA of a group, here

All of these posts use Matches who share DNA segments with you, and ThruLines adds the added dimension of genealogy – using the power of Ancestry’s huge database of Trees. ThruLines usually uses multiple Trees which are in agreement. This is a good, easy, place to start – a good hint – but like all such “hints” you should validate the result. Yes, some of the Trees are flawed, but most are not. Based on my 45 years of genealogy research, I’ve found ThruLines to be correct about 95% of the time.

This post is about another way to use the power of ThruLines – checking on a suspicious branch of your Tree.  Suppose you have a Tree and have been documenting Matches who have Common Ancestors with you. And you notice that one branch of your Tree isn’t getting as many Matches as you expected. It may be because the branch is one that recently immigrated to the US; or because the Ancestors in the branch had relatively few children. Both reasons would tend to reduce the number of Matches from that branch. But if you’ve ruled those reasons out, what’s left? Well, the elephants in the room are a non-biological parental relationship in your Tree (an NPE or MPE) or faulty genealogy research.

One way to check a suspicious branch is to use ThruLines, as follows:

1. Determine the Ancestor who is the base of the suspicious branch – use your judgment.

2. Click on the child who is your Ancestor

3. Open that (child) Ancestor’s profile page

4. Open the Edit tab (top right)

5. Select Edit relationships

6. Click on the X next to the suspicious parent(s) – one or both

This will remove the suspicious branch from your Tree. It will also preserve all the work you’ve done on that branch, and at any time you can easily go back to the child (#2 above) and add the parents back in using the Select someone in your tree option (just type in the names you had before and select them).

After you’ve removed the suspicious branch,  just wait a few days. ThruLines will try to find Matches who are cousins from this line and will identify Potential Ancestors the fill in any gaps. This works out to the 6th cousin (6C) level – your 5xGreat grandparents. If ThruLines identifies Potential Ancestors who were the Ancestors you originally had – well nothing lost (but be sure to use the Select someone in your tree option to get back the branch as you originally had it). If ThruLines identifies alternative Ancestors – well then, you’ve got some work to do to understand more about those Ancestors and decide which Ancestors to use. Remember the ThruLines version is just a “hint” – it’s still up to you…

What I would do is accept the ThruLines Potential Ancestors (later, they can always be deleted or removed from the Tree with Steps 1-6 above) and see if I got a more ThruLines Matches than I had before. If so, these ThruLines Matches would have Trees that should be reviewed for additional evidence. My go-to evidence is the census records if they are available for these new Ancestors – are the times and locations appropriate? At this point, this is mainly a genealogy exercise, although a review of relationships and Shared cMs should also be done.

This is yet another way to use the power of ThruLines. It’s not guaranteed to work, but it does give you a quick and easy look into the huge Ancestry inventory of Trees for potential alternatives.

[22BB] Segment-ology: Do You Have a Suspicious Branch in Your Tree? TIDBIT by Jim Bartlett 20210928

12 thoughts on “Do You Have a Suspicious Branch in Your Tree?

  1. This is very interesting. Using Thru-lines, I noticed some empty lines. I have “cleaned” up many by checking in the “Edit Relationships” feature to make sure all of the children are listed as “Biological” and not “Unknown.” These tend to be ancestors who I added 20+ years ago with Family Tree Maker, then PAF. I also had a lot of spouses listed as “Unknown” instead of Spouse, but I’m not sure that made a difference.

    I am trying your method on two suspicious lines in my mother’s tree, which I haven’t worked on. Very endogomous and 160k matches. Will check back in a few days to see if Thru-lines worked it’s magic.


  2. Thank you for your helpful article. I have a suspicious branch, leading back from my great-great grandparents. I have DNA matches from my great-great-grandmother’s ancestors, but I have no DNA matches to my great-great-grandfather’s ancestors. They had only one child, my great-grandmother, who appears to have a discrepancy in her date of birth. It seems possible that she was not the biological child of my great-great-grandfather. It is possible that I inherited none of his DNA, also, but neither have other relatives.

    A few years ago, I found a large cluster of DNA matches who are in the 3rd-4th cousin range, but I find no common ancestors with them, so that cluster has been a puzzle. The only place on my tree where I haven’t confirmed my ancestry with DNA triangulations is this suspicious branch, so I’ve tried your suggestion today on ThruLines to see if it comes up with a surname.


    • Sandra, Great! I hope you’ll give us some feedback on how it goes. Also, I’d be studying any Trees in your puzzle cluster to see if those Matches have a Common Ancestor among themselves… I’ve found 3 such groups now, and added many of my Matches to each groups once I determined the MRCA – for each group the Matches mostly share Matches with each other (Cluster)… Jim


    • Fredrik, I don’t think so – let’s think out loud here. ThruLines needs a toe-hold, some link, something to go on. If you removed a parent, ThruLines would only have two base people to work from – you and the other parent. I doubt that someone else in the world would have you in their Tree, or with the correct bio-parent. By the same token, I doubt that anyone would have your other parent in their Tree mated to the correct bio-parent. There is nothing solid for ThruLines to work from on an unknown bio-parents line. In the process I outlined in the blog-post, the child is usually pretty well known (and if not drop down another generation to a firmer Ancestor to use as a base for ThruLines)/
      In your case I would use the other method to try to determine a bio parent. Look at your top Matches at AncestryDNA – look for Matches with Trees (even just 2 or 3 generations may help). You are looking for how these closest Matches are related to each other. Do NOT, at this point, try to tie them to your won ancestry – just try to tie them to each other. You might have to research and extend the Ancestors of some of them. With enough Matches, you should be able to form two or three or four Trees – depending on how far down your list you go. The fact that they are your closest Matches means they are your closest cousins, and should have Common Ancestors (bio-Ancestors) with you which are not too distant – probably your bio-grandparents or great grandparents (you can estimate this based on the birth years). When you’ve identified some families, focus on finding their children and grandchildren. Somewhere among them is usually someone from one family who married someone from another family. By now you may have noticed that one group of families is from your other, confirmed, parent’s side – you can set those Matches and families aside, and focus on the remaining Matches and families. Particularly when you find an intermarriage, you are almost certainly on the right track. Now, add the man and woman who married into your Tree. Look at their ages to see if they are probably grandparents or great grandparents and then fill in the appropriate blanks in your Tree with the word Private. You don’t need dates or places, just a block to represent your Ancestors back to the couple. Now wait for ThruLines to work it’s magic. If these are indeed your grandparents or even great grandparents, you should get a lot of ThruLines Matches with Common Ancestors being this couple or their Ancestors (fill in those Ancestors if you can). IF you do get a lot of Matches, you are probably on the right track. If you don’t, keep digging among your closest Matches… In general, this is not a long or laborious process – it’s usually pretty quick, and can be done on a scratch pad: List the closest Matches, open Trees and jot down the surnames back 3 generations or so; look for Matches who have the same surnames and sketch out their Trees – the goal to form one family for each repeated surname; then look for intermarriages (this last step requires a little digging, but the other steps are pretty easy. Please post back your experience. Jim

      Liked by 1 person

      • Thank you Jim for providing such a detailed answer! I just found it last week, and following your reasoning above, I could add a private block, as the father, since he is the MRCA of 5 matches on MyHeritage, and was also given this tree position in the highest ranking hypotheses from WATO. It just hadn’t even crossed my mind earlier that a Private block would yeild ThruLines output, but it sure did. I got 11 ThruLines matches ranging from 9 cM to 77 cM. So I’ll have plenty to work with, much appreciated! 😀 🙏

        Liked by 1 person

      • Frank – Congratulations. You have a “block” for every one of your Ancestors going back as far as you want. Each block had to be there, or you wouldn’t be here. Similar for the DNA – each segment is fixed in your DNA – uniquely to you. Neither of these ever changes. Our job is to figure them out, to solve the jigsaw puzzle, to fill in the blanks, to paint the picture – use whatever phrase you want. AND, all of your true Matches link into your DNA and Ancestry only one way.
        Shared Matches have a kind of magnetism – they are drawn to us and to each other by an invisible force (created by the fact that we are interrelated). So even if you have a no-name block in your Tree, your Matches will still be drawn to you.

        Good luck on your quest. Jim

        Liked by 1 person

  3. One of my ThruLines matches (through one of my 4G grandfathers, Ralph G Vandalinda) was through a child of Ralph’s not on my tree. I checked my references, including Ralph’s will, and found no trace of a child of that name in Ralph’s family. However, Ralph’s first cousin, Ralph J. (son of Jacobus VDL instead of Guilliam VDL), did have a child with that name. A rare instance where ThruLines, in effect, looked back to 6G grandparents.


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