Using Y-DNA and Autosomal DNA Together to Close a Gap in the Nicholas Ackley Family Tree

In past posts on this blog, I’ve written about members of the Ackley Surname Project who have learned that they are descendants of Nicholas Ackley through Y-DNA testing, but did not learn enough to know exactly how. At this stage, the project has enough descendants for each of Nicholas’s sons to define a branch for each son. But each son does not yet have enough branches to allow us to trace lineage down the generations without encountering gaps.

As noted in earlier posts, associations can be determined using more than one method. This project uses Y-DNA, which traces only the males in a lineage. Autosomal DNA traces both the male and the female lines and is used by companies such as Ancestry and MyHeritage. What follows is an example of how both types of DNA may be needed to bridge the gaps and  resolve lineage issues.

This story starts with Nancy Mattison, the author of the excellent book Discovering Nicholas Ackley, Early Connecticut Settler 1630-1695. Nancy also writes a blog on Nicholas Ackley and his descendants, and sometimes gets questions from people looking for help with their Ackley genealogy. Someone who is a descendant of Zebulon Ackley had asked her for help, and she thought DNA might help answer his question and contacted me (see her description of this query here [1]; be sure to click on the link in the post to get a PDF document with all of the details about the process and Zebulon research). We soon learned that this person's father was actually already a member of the Ackley Surname Project who can trace his male Ackley line back to Zebulon Ackley, born about 1775 and died in 1812 in New York. This relationship is pretty well documented up to Zebulon, but at that point it reaches a dead end. This member had done a Y-67 test and matched all of the Ackley men in the project who have known relationships to Nicholas Ackley, so we are nearly 100% sure he is a descendant of Nicholas, but he wanted to discover the connections all the way up to Nicholas.

First Step: Big Y

The first step was to take a Big Y test to try to place this member on one of the branches in the haplotree representing one of Nicholas's sons. A Big Y test was purchased, and the results placed the member on the branch for Nicholas's son James (in fact it created a sub-branch, which will be discussed shortly). We are confident this is the James branch because we have a couple of project members with well-documented paths through James to Nicholas. The block tree before the new Big Y results were obtained is shown below. The numbers in the white blocks at the bottom of the tree are test kit numbers for Big Y testers in the project, and the R-XXX codes in each block represent the Y-DNA mutations that define the branches (blocks) in the tree. Each of the testers has tested positive for the mutations in all of the blue blocks above them. For example, tester 947514 is positive for mutations R-FTA50959, FTA49307, R-FT165378, R-FTA24085, R-FGC52286, BY53874, and FGC52298.

Note that the leftmost block under the James block (R-FGC52300) is a sub-block of the main James branch (R-FT82490). This branch became separate because the two members on it are closely related (a father and son). They matched each other on the mutations listed in that block (which no other testers have), so they established their own block under James. They are known descendants of James's son Nathaniel, so their block represents Nathaniel's branch. On the other hand, the two testers who are in the James block are not closely enough related to create their own branch under James and each one still has some private variants (mutations found in no other tester so far), so they remain in the more general James block. Tester 754287 has a well documented path to James, while tester 985409 has a gap between his earliest known Ackley ancestor and James.

After the new Big Y results for tester 205619 were available, the block tree looked like this:

Note that the new Big Y tester and one of the previous Big Y testers now occupy their own block under the James block. This happened because the new tester (205619) had some variants that matched some of previous tester 754287's private variants; i.e., mutations that were only found in tester 754287 so far. These private variants are now named because they were found in more than one tester, establishing a new branch under James. Tester 754287 is a known descendant of James's son Nicholas (we'll refer to him as Nicholas-2 to avoid confusion with our original immigrant ancestor Nicholas). At this point we can conclude that the new tester is also a descendant of Nicholas-2, but we still have a gap. Nicholas-2 was born in 1708 and died in 1763, while Zebulon was born about 1775, so Nicholas-2 cannot possibly be Zebulon's father. There must be at least one more generation between Zebulon and Nicholas-2.

Translating that to a more traditional family tree, we have this for the testers who are descendants of James:

I have marked the last few generations in each tester's line as private to protect their identities. Note that tester 985409 is left "floating" since we only know he is a descendant of James, but not which son yet. Tester 177515 does not appear in the block tree above because he has only done a Y-37 test and thus does not have his branch identified in the haplotree yet. Having him do a Big Y test remains a goal for the project.

The question is: How do we close the gap between Zebulon and Nicholas-2? One approach would be to find more known descendants of Nicholas-2 to do Big Y tests and establish sub-branches for Nicholas-2's sons on the haplotree. This is certainly a long-term goal of the project, but there are a few problems with that approach. Identifying known descendants and then persuading them to test is a tough task, Big Y tests are expensive ($449 at regular price and $399 on sale), and they take a long time (up to 12 weeks from receipt of sample at FTDNA to final results). While not insurmountable, these issues caused us to look for a different way to try to solve the mystery of Zebulon's parentage and hopefully close the gap between Zebulon and Nicholas-2.

Before jumping into the next section, it is worth discussing the possibilities for Zebulon's father here. Nicholas-2 had four known sons: Jeremiah (1742-1761) and Abel (1746-1835) with his first wife Jerusha, and Lewis (1758-1823), and Nicholas-3 (1762-) with his second wife Sarah Wilson. Given Zebulon's birth date of 1775, Jeremiah could not be his father since he died in 1761. Lewis (born in 1758) and Nicholas-3 (born in 1762) are too young to have been Zebulon's father. This leaves Abel or an as yet undiscovered son of Nicholas-2 as possibilities for Zebulon's father.

Another DNA Tool

Here is where we turned to autosomal DNA to help solve this mystery. Autosomal DNA testing is the most common type of DNA testing used in genealogy, and is the type of test that can be purchased from many companies, such as Ancestry or MyHeritage. Ancestry provides the following description of autosomal DNA:

"DNA comes in long stretches called chromosomes. Humans typically have 23 pairs of chromosomes for a total of 46. There are two broad categories of chromosomes—autosomal and sex chromosomes.

• Autosomal chromosomes—22 matching pairs—make up the bulk of your DNA. Almost everyone has a complete set of them. An autosomal DNA test looks at the DNA from these 22 chromosome pairs.
• Sex chromosomes are made up of X and Y chromosomes, which differ in size and function. People usually have either a pair of X chromosomes or X and Y chromosomes." [2]

The Y-DNA testing discussed at length in this blog is done with the sex chromosomes mentioned above and gives only information about the patrilineal line. We turned to the autosomal chromosomes to help us close the gap. Autosomal chromosomes contain DNA from both parents and thus can be used to gather information on the male and female ancestors in a tester's family.

I don't want to get too far down into the weeds on the biology of autosomal chromosomes, but I wanted to provide a look at how autosomal matches are measured and evaluated. The unit of measure for autosomal DNA is the centiMorgan. Family Search has this to say about centiMorgans:

"A centimorgan is a unit of genetic measurement. It’s what experts use to describe how much DNA and the length of specific segments of DNA you share with your relatives. These shared segments are divided up into centimorgans. The more centimorgans you share with someone, the more closely you are related. A centimorgan is different from the physical units we use in everyday life, such as inches or kilometers. It is less of a physical distance and more of a measurement of probability. It refers to the DNA segments that you have in common with others and the likelihood of sharing genetic traits." [3]

All you really need to remember is that a centiMorgan is a relative measure of the amount of DNA shared between two testers, and the more centimorgans shared, the closer the relationship.

The various testing companies have come up with estimates of relationships based on the amount of shared DNA, but I prefer to use real data to evaluate matches. Blaine Bettinger, a genetic genealogist, has collected mountains of real data from fellow genealogists and has made it available to the genealogy community. He asked users to report the amount of DNA they share with people whose relationship is known to them. He then summarized the data for all different levels of relationship, from parent/child all the way up to 8th cousins and everything in between, including half relationships and "removed" relationships. The table below shows the data for common relationships. The average column is the average shared cM reported by users for each type of relationship, and the range column gives the low to high values reported for that relationship. We'll use these values below to evaluate some of the matches we found.

Shared cM Project Relationship Data [4]

  

Tester 205619's daughter did an autosomal DNA test with Ancestry, and we sorted her matches into family groups representing maternal and paternal grandparents to help reduce the number of matches we needed to analyze. Then, we began looking at the matches for the paternal Ackley group. This type of analysis is somewhat time consuming because we had to either verify existing trees for the matches or even build out sparse trees to go back far enough to be able to compare to what is known about Zebulon. We found many matches who were descendants of Zebulon's children, especially for his sons Ira and Salmon. While not necessarily helpful for discovering Zebulon's parentage, these matches serve to verify the tree is likely correct up to Zebulon. A summary of these matches is shown in the blue and orange boxes in the "Autosomal DNA Matches on Ancestry" chart below.

There was another group of matches who are descendants of Abel's children, which is good news for the theory that Abel and his wife Hannah could be Zebulon's parents. Remember from above that we ruled out Nicholas-2's sons Jeremiah, Lewis, and Nicholas-3 as possibilities for various reasons, but we left open the possibility that Nicholas-2 had another son that we don't know about. So, we need to evaluate the matches we've found to see if we can rule that in or out. To do this, I created the table below that shows the relationships between our tester and her matches if we assume Abel and Hannah are the parents, along with the associated expected shared cM and ranges. This is compared with the same information if we assume Zebulon's parents were an undiscovered son of Nicholas-2 (we'll call him Zebulon, Sr.) and his wife (probably named Elizabeth - it seems like half of the women alive during that time were named Elizabeth!). In that case, there would be another generation between the tester's daughter and her matches who are descendants of Abel and Hannah because Nicholas-2 and Jerusha would be the common ancestors. Here is the table:

You can see that in both cases, the shared cM of the tester's matches are within the observed ranges suggested by real data for the relationship. Match number 1 is very close to the top of the range in the Zebulon Sr. scenario, but still within it. The shared cM values are not too far off from the expected values in either scenario, so overall there is really nothing in the data that would cause us to choose one theory for Zebulon's parentage over the other. We need something else to help us solve this problem.

What we found was a group of matches who were descendants of Richard Shevalier, who is the brother of Abel's wife Hannah Shevalier. These matches to the Shevalier line appear to be independent of the Ackley line; i,e., we found no intersection between the Shevalier and Ackley matches. Although it is possible that our theoretical Zebulon, Sr.'s theoretical wife Elizabeth was an unknown daughter of Hannah and Richard's father Elias Shevalier, it is far more likely that the tester's daughter has autosomal matches to both the Ackley and Shevalier lines because Abel Ackley and Hannah Shevalier are Zebulon's parents. Big Y testing of a known Ackley male descendant of Abel Ackley could solidify this conclusion, but the autosomal matches discussed above are strong evidence that we have discovered Zebulon's parents.

The various groups of matches are summarized in the family tree below, with the number of matches found for the family members in the colored boxes. Side note: there are probably more matches to be found for each group, but given the time it takes to identify them and verify/build their trees, we chose to use what we had as a representative sample. Additionally, there are more Shevalier and Ackley children that were left off of the chart in the interest of keeping the diagram uncluttered and readable.

Link of the Day

This is a link to a technique called the Leeds Method, which is a simple, systematic way to segregate autosomal DNA matches into family groups. It was the method used to sort the matches into groups by grandparent discussed in this post.

https://www.danaleeds.com/the-leeds-method/

Quote of the Day

“Live as if you were to die tomorrow. Learn as if you were to live forever.”

― Mahatma Gandhi

Sources

1. Nancy Mattison, "Was Zebulon Ackley a Son of Abel?," Discovering Nicholas Ackley (blog), June, 2024, https://ackleygenes.com/2024/06/25/was-zebulon-ackley-a-son-of-abel/.

2. “Autosomal DNA Testing | AncestryDNA® Learning Hub,” n.d. https://www.ancestry.com/c/dna-learning-hub/autosomal-dna-testing, accessed 11 Jan 2025.

3. FamilySearch. “Untangling the Centimorgans on Your DNA Test,” October 3, 2023. https://www.familysearch.org/en/blog/centimorgan-chart-understanding-dna, accessed 14 Jan 2025.

4. International Society of Genetic Genealogists. "Autosomal DNA Statistics," October 17, 2022. https://isogg.org/wiki/Autosomal_DNA_statistics, accessed 14 Jan 2025.