When we find an autosomal match in genetic genealogy, and we then discover that person shares a common ancestral line with us, we do our happy dance and tend to forget that they might actually share a second line as well.
It’s easy to discount in the excitement of the moment, especially if you’re working in a situation where your match to that ancestral line on that segment has not been proven by triangulation.
But let’s face it, all genetic genealogy success stories, whether just one to one matches or triangulation begin with individual matches.
So, I was curious, just how many of our matches really do share a secondary genealogy line.
Now, let’s be very clear here about what a secondary line is, and is not.
This is my father’s pedigree chart.
They automatically share the lines to the right of those ancestors in the pedigree chart – those who contribute to the DNA of Samuel and Elizabeth. In this case, that would be Fairwick Claxton, Agnes Muncy, Charles Speak and Ann McKee.
As we move the pedigree chart out further in time – that list of common ancestors that we do share would include everyone on this chart including and beneath the blue cell, James Lee Claxton. These are NOT secondary lines, just ancestors of the people in the original match that we would also expect to have received some amount of DNA contribution from.
That is a secondary line, not connected genetically to the first line.
Obviously, if the person we match has ancestors living in the same geography as our ancestors, there’s a possibility that they will share a second (or even third) ancestral line.
How often does that actually happen?
I’ve been working with my shakey leaf matches at Ancestry.com. Shakey leaf DNA matches are those with whom Ancestry has identified that you have a DNA match and a common ancestor in a tree. I love shakey leaves!!!! They save me so much work.
Now, the easy assumption to make is that your DNA match is through the ancestor noted on the tree. That’s certainly possible, and if that is your only common ancestor, it’s even probable – but without a chromosome browser and triangulation there is NO PROOF.
There is no way at Ancestry to prove a genetic relationship. But that doesn’t mean you shouldn’t gather evidence.
I’ve been keeping a spreadsheet of matches at Ancestry, our common ancestor, which child they descend from and any other known common lines.
I have a total of 137 rows, each representing a shakey leaf match at Ancestry.com.
Of those, 16 disappeared with Ancestry’s new phasing rollout in November. No, I am not “over that”…nor do I think it’s accurate because I match some of those same people elsewhere and triangulate with common ancestors. Nuff said about that – no point in beating a dead horse.
Recently, Ancestry has added a feature that allows a hint to additional shared ancestors. However, on mine, which is all I can really address, all of my multiple hints were to people in the same line where Ancestry appears to have been confused, perhaps by people’s trees.
For example, the three hints on the match below includes one, as shown, one to only the mother (Suzanna Berchtol) and one to their grandson’s wife’s mother (but not her father.) But there was no match to the son and his wife. These are not inaccurate, just confusing.
None of my multiple hints were actually to different lineages – although several matches’ trees do exist that include unquestionable matching to multiple lines.
Ancestry includes a great comparison feature.
If you view your shakey leaf match, they show you the common ancestor of both individuals in a tree, as show below with cousin Harold.
If you scroll down, you will see the list of common surnames we share – in the green box on the left.
Because I know my own tree quite well, along with cousin Harold’s, I know by just looking at this list that all of these except one are from the same line as Joel Vannoy and Phoebe Crumley, our common ancestors.
But, for purposes of example, let’s say that I discover one that isn’t.
Let’s say Mercer isn’t a name from our known common line.
By clicking on Mercer, you can see that yes, indeed, we do share a common ancestor. Hannah Mercer appears recognizably the same in both trees.
Looks like cousin Harold has more Mercers than I do, so I need to visit with cousin Harold about this.
Now let’s look at Webb, our name that is not from this common line.
Webb doesn’t match. Furthermore, I haven’t entered anything about this person that even remotely identifies them, so I need to address that. Even approximations are useful, and no information at all is not useful.
I went through this process for every single common surname for each tree that I match. Of interest, there were only a few trees that didn’t have any surnames that I needed to check.
On top of the matches I lost through phasing, we need to subtract another 21 for private trees and one more because their tree won’t load due to a technical issue of some sort. Of the 21 private trees, I have written to all 21, and 4 of the individuals answered me by telling me the name of our common ancestor. However, that still does not provide me with the ability to see this page that shows our common matching surnames.
That leaves me with 99 shakey leaf matches whose trees I can see.
Of those, 52 do not have a common ancestor or a common line that makes me think we might have a common ancestor. What the heck does that mean?
It means that roughly half of my matches either do or might have a secondary matching line.
Let me give you a couple of examples that make it difficult to decide.
Campbell – those darned Campbells. First, I’m at a dead end with mine in Hawkins County, TN around 1800. We do have a Y DNA representative from my line though, and we know that our Campbell line matches the Campbell clan line. So, anyone where I see Campbell in their surname list, regardless of how far back in time that Campbell link goes – I categorize as “possibly Campbell.” Because, frankly, we not only don’t know for sure how long that sticky DNA can stick together and I don’t know which line my Campbells descend from in 1700s Virginia, assuming that is where they came from.
Secondly, Hall. My Hall family was from Tolland County, CT. When I see someone else’s tree that shows a Hall ancestor from Tolland County, CT, even though they don’t connect with mine – I know darned good and well there is a very high likelihood that this is the same Hall family as mine. So, I categorize that as “probably Hall.”
When I find a dead hit in terms of a common ancestor, I just enter their name in that column
I have 4 that I’ve categorized as “not recognizable” which means to me that it looks quite suspicious in terms of surname/geography, but no smoking gun like Hall in Tolland County. I’m combining these with the “no” group for now, understanding that a “no” could turn into a “yes” with a breakthrough for anyone at any minute.
I have 13 labeled “possible.”
I have 7 labeled “probable” but ironically, two of those have two lines each that are not connected to each other.
I have 8 that are Acadian, meaning they descend from a large group of common surnames from the Acadian community. This is a highly endogamous community and it’s nearly impossible to tell which DNA comes from where and originally belonged to whom. This means that lines on my chart that appear to be disconnected probably are not. I view these as all “yes” in terms of multiple lines.
I have 15 matches with positively confirmed secondary lines, and of those, another 5 possible third lines.
So how does this stack up:
|% Matches||56||13||7||8||15||10 + 8 Acadians|
Truthfully, this is far more than I expected. I thought it would be the rare match where I would have two disconnected genealogical lines. In reality, it appears that it could be about half the time. This certainly causes me to take a moment to pause and reflect – and makes triangulation even more important.
What this really means is that we cannot assume that DNA/Tree matches are connecting the dots between the right genetic lines and the right pedigree lines in a tree – because about half of the time, it could be the wrong line in our and their tree. And this little experiment, by the way, cannot take into account the dead ends on either my tree or theirs that can’t be accounted for.
Let’s be very clear about this. You DO share DNA with this person from a common genealogical line. You MAY share DNA with this person from multiple lines. The DNA may NOT have come down to you from both (or multiple) lines. From tools we have at Ancestry, we can’t tell which line or lines contributed the DNA.
The only way to prove a match is to a specific ancestral line is to triangulate the match, meaning that the same segment of DNA matches between a minimum of three people who share the same ancestor. To do this, you need a chromosome browser, which Ancestry does not and says they won’t provide.
More and more Ancestry customers are transferring their results to Family Tree DNA and to GedMatch to take advantage multiple pools and tools. So, you can’t prove a relationship at Ancestry, but there is still a lot of useful work that you can do based on your matches trees…so long as you don’t need proof. In the next few days, we’ll be talking about how to maximize your AncestryDNA experience.
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