I’m starting this year by checking in on my tree completeness. Why am I doing this? While it can be nice to keep tabs on genealogy research progress, and I like a good set of statistics as much as the next person, it’s more than just curiosity. For any research project, it’s useful to start by evaluating what’s known and what’s not known (or not confidently concluded). Taking a look at what’s in my tree – and where there are gaps – can help me to focus on what research steps I might want to take next.
Beyond that, examining the state of a family tree is critical for incorporating DNA evidence into any conclusions made about relationships to genetic matches, and is therefore critical for using DNA evidence to prove genetic ancestry. It’s even written into the Genealogy Standards (Standard 52) that as part of our analyses of DNA evidence, tree “accuracy, depth, and completeness” (among other factors) should be evaluated for match comparisons to be able to draw conclusions about genetic relationships.1 We need to understand the completeness (and accuracy and depth) of our own trees and of those of our DNA matches so that we can properly discern what ancestral line or lines we might share. Testing hypotheses about what ancestors we might share with our matches needs to include not only evidence in support of each hypothesis, but also evidence rejecting alternatives. And how can we reject the possibility of the overlap of branches that we know nothing about? We need to know about the trees of both ourselves and our matches to actually make comparisons and rule in or out possible origins of shared DNA. Blaine Bettinger wrote a blog post a while back discussing these ideas: How Much of Your Family Tree Do You Know? And Why Does That Matter?
One of the tools that I like for evaluating tree completeness is the Tree tool at DNA Painter. With a free account, users can enter details for a single family tree (or import a GEDCOM tree up to the 4th-great-grandparent level; users with paid subscriptions can import all generations of a tree and have up to 50 trees at the site). Among other nice features, when family trees are entered at this site, there is a link at the upper right of the Tree page titled “Tree completeness” (see screenshot of part of my tree at this site). Clicking this link displays a pop-up window showing the completeness of the tree at each generation.
Another useful strategy can be to simply keep track of counts of identified ancestors in a spreadsheet; this can allow for additional flexibility in how the results are calculated or displayed. An Excel template for this was posted to the Genetic Genealogy Tips & Techniques Facebook Group (also by Blaine Bettinger, in 2019); the file is called “How Much of Your Tree.xlsx” and is available in the Files section of the Group page.
I’ve modified and copied parts of the original spreadsheet in a new file to see how my numbers have changed over time (shown here). For the purpose of these counts, I’m including “known” ancestors as those for whom I’ve identified at least first and last names with some documentary support. In the case of pedigree collapse (where a single individual might appear as an ancestor in more than one line), I’m counting that individual multiple times – once for each possible ancestor slot they fill.
If you take a close look at my numbers, you might notice that I have made some progress in the past three years, though perhaps not much of an improvement on overall number of ancestors identified. I have added a few ancestors’ names to my tree since early 2019, but I’ve also removed a few. Some of these may not stay removed permanently, but once I realized that the evidence of their connections to my lines was somewhat questionable, I took them off. Though I’d like to see these numbers continue to grow and my percentages improve, I’d rather have a higher quality tree than just a larger tree. So, I’m reasonably happy to see that I’ve made progress not only through adding names, but also through pruning a couple of iffy branches. Moving forward, I certainly do hope to spend more time strengthening evidence for ancestors already in my tree and finding well-supported new ancestors to add.
What about trees with (big) gaps?
Whether we’re looking at our own trees or at those of our DNA matches, we will certainly come across gaps in the ancestors identified – often at earlier generations than we’d like. While much of our genealogy research is done with the goal of filling in those gaps, we all know that some ancestors are harder to find than others. We should, of course, continue to strive to fill in gaps in our trees as much as possible, especially when the goal is to prove genetic relationships with others. We can still make some tree comparisons between ourselves and our DNA matches when there is tree incompleteness in recent generations, however.
One strategy is to consider the locations of origin of different branches of the tree(s) of interest. My husband’s tree, for example, has more gaps than my own (for a number of reasons, including that I haven’t spent as much time researching his ancestors as I have my own). We only have seven of his eight great-grandparents fully named with confidence, and we’ve identified fewer than 10% of his 4th and 5th great grandparents so far. For his ancestors that we know with reasonable confidence, though, their lines appear to come from distinct areas of Europe (see diagram). Since documents suggest that four of his great grandparents were born in Ireland, two were born in France, and two were born in or near Poland (and his DNA ethnicity estimates appear to be consistent with these origins), it is often easy to form hypotheses narrowing down which branch(es) of his tree he might share with DNA matches.
Looking at common geographical regions of origin is not a foolproof way to determine shared ancestry; people migrate across regions, and documents stating birth places can be wrong. See the DNA Frequently Asked Questions page on the website of the Board for Certification of Genealogists for a much more in-depth discussion about details of including pedigree analysis while incorporating DNA evidence that meets Genealogy Standards, including topics such as “What is pedigree evaluation?,” “What is required for pedigree evaluation?,” and “What are some strategies to mitigate pedigree problems?”
None of our trees are perfect, and none of them will ever be “done.” But it can be a good idea to check in from time to time to assess the gaps in our trees, so we can better evaluate the strengths and weaknesses of our arguments and target our research efforts moving forward.
1. Board for Certification of Genealogists, Genealogy Standards, 2d Edition. (Washington: Ancestry.com, 2019), 30.