In my last post about autosomal DNA coverage, “Find More Ancestors with Autosomal DNA by Increasing Coverage,” I discussed how testing multiple descendants of your research subject can help you find more relevant matches. I shared some examples of applying Paul Woodbury’s coverage formula and the Daniel Arnold project I’ve been working on.
Today I have an example of how expanding the coverage of Barsheba Tharp helped solve the identity of her mother. Barsheba Tharp and John Robert Dyer are my husband’s 3rd-great-grandparents. They lived in Hawkins County, Tennessee from at least 1830-1880. Barsheba Tharp was born in Hawkins County in about 1813-1818. John Robert Dyer’s origins are still in question but he was born about 1810-1813 in Tennessee or North Carolina. I began researching this couple with the hope of extending the Dyer patrilineal line.
My father-in-law took the AncestryDNA test and the FamilyTreeDNA Y-DNA test. I also asked my father-in-law’s two brothers to take the AncestryDNA tests and transferred their tests to MyHeritage, FTDNA, and GEDmatch. I ordered a ConnectedDNA network graph showing genetic networks for the three brothers’ combined matches.1
As I reviewed their matches, I found many matches whose ancestry went back to Tharps in Hawkins County, Tennessee. I switched my focus from finding John Robert Dyer’s parents to finding Barsheba Tharp’s parents. I found that Lewis Tharp was Barsheba’s father, but determining which of his two wives was Barsheba’s mother was trickier. Lewis married Joanna West first, and after her death, he married Judy Vernon.
At first, I thought Barsheba’s mother was Judy Vernon, the 2nd wife, because her descendants shared so much more DNA with Barsheba’s descendants. However, there was some conflicting evidence with Barsheba’s birth year being before the time of Lewis Tharp’s marriage to Judy Vernon in 1817. Then, I found some DNA matches going back to Joanna West’s side of the family, making the hypothesis that Joanna West was Barsheba’s mother more likely.
In the recent Research Like a Pro with DNA study group, my research objective to test this hypothesis was:
Determine if Joanna West was the biological mother of Barsheba Tharp. Barsheba was the wife of John Robert Dyer and they resided in Hawkins County, Tennessee from 1830-1880. Barsheba was born about 1813-1818 in Hawkins County, Tennessee, and was the daughter of Lewis Tharp, born 1786 in Fauquier County, Virginia. Lewis was married twice, first to Joanna West in 1805 in Fauquier, Virginia, then to Judy Vernon in 1817 in Hawkins, Tennessee.
Joanna West’s parents and grandparents had already been documented by a fellow researcher who sent me many documents and land plats. Here are the ancestors of Joanna:
If my hypothesis about Joanna being the mother of Barsheba Tharp was correct, I thought I would find many matches to descendants of John West and Bathsheba Arnold; as well as matches to descendants of Humphrey Arnold and Harriett Ann Smith. I used the network graph of my father-in-law and his two brothers to look for these matches. I searched pedigrees of DNA matches in clusters that were connected to Barsheba Tharp’s cluster, but I ended up finding no connections that furthered the hypothesis. It was frustrating!
In my previous research to discover John Robert Dyer’s parents, I had asked multiple descendants of John Robert Dyer and Barsheba Tharp to share their DNA results with me on Ancestry. To this point, I hadn’t really analyzed their results and looked for matches that would help with Barsheba’s mother. I decided to go ahead and expand my analysis of DNA matches to another test taker, who I will call Sally. I created a network graph (using Gephi software) for Sally’s matches at Ancestry from 12-240 cM. Then, I isolated clusters that included Barsheba Tharp’s descendants and connected clusters. I reclustered those matches to create a cleaner network graph that only had relevant matches. I found a cluster that had several matches whose trees traced back to Joanna West’s grandparents, Humphrey Arnold and Harriett Ann Smith!
Here is my analysis of Sally’s network graph:
- 0 (Pink): Sharing from 12-199 cM
- Tharp descendants from Fauquier, Virginia – probably Lewis Tharp’s relatives
- Match H, descendant of Barsheba Tharp and John Robert Dyer
- 1 (Green): Barsheba Tharp and John Robert Dyer descendants – includes the Dyer brothers
- 2 (Light blue)
- Match N, descendant of Lewis Tharp and Joanna West > Elizabeth (Tharp) Parrott
- Match E, descendant of Lewis Tharp and Joanna West > Elizabeth (Tharp) Parrott
- Match D, descendant of Lewis Tharp and Joanna West > Elizabeth (Tharp) Parrott
- Match H, descends from Daugherty/Taylor group from Craven County, NC (probably John Robert Dyer’s mother)
- 4 (Blue): matches from 12-48 cM
- Match J, descendant of Humphrey Arnold and Harriett Smith
- Match T, descendant of Humphrey Arnold and Harriett Smith
- Match M, descendant of Humphrey Arnold and Harriett Smith
This was what I had hoped to find with the network graph of the Dyer brothers! I was thrilled to see evidence of DNA matches from Joanna West and her grandparents, Humphrey Arnold and Harriett Ann Smith. It appeared that the entire blue cluster would provide helpful evidence, if I could expand the matches’ trees far enough. After doing this analysis with Sally’s matches, I checked to see if the other test takers shared DNA with them. Many times, I found that my father-in-law and his brothers shared DNA with these matches, but just in smaller amounts that weren’t included in the network graph (which only went down to about 25 cM). This is also a challenge when using shared matches at Ancestry, since it doesn’t show shared matches less than 20 cM. Luckily, I was able to find the matches who shared more with Sally, then check how much those matches shared with my other test takers by going to the match’s Ancestry profile page and using the drop down box to do comparisons.
I continued to use shared matches of these matches to find additional descendants of Joanna West’s family. Through this process, I found matches who also descended from Joanna West’s parents, John West and Bathsheba Arnold.
Because these ancestors are 5-7 generations removed from the test takers, the amounts of DNA shared were small, and not all the test takers shared with all the matches. This made it especially important to have a large group of test takers who had shared their results with me. With just my father-in-law’s and his brothers’ matches, I wouldn’t have had enough DNA matches sharing over 15 cM of DNA to make the case. If all the amounts of shared DNA were less than 15 cM, it would have been weak evidence. Some of those segments could be false. But because I had results from Sally and other descendants of Barsheba Tharp, I was able to find sufficient evidence to show a connection to Joanna West and her parents and grandparents. It’s best to have more than one of your test takers sharing with a distant match to show evidence that they are connected along the line in your hypothesis. It’s also best to have matches who share more than 10-15 cM.
Coverage of Barsheba Tharp and John Robert Dyer
To illustrate the difference in the coverage of Barsheba before I included more test takers, I created two diagrams showing the coverage of Barsheba Tharp and John Robert Dyer. Figure 1 shows the estimated coverage using only the three Dyer brothers’ DNA. Figure 2 shows how much the coverage was increased by adding in test takers through multiple independent child lines of Barsheba Tharp. With just my father-in-law and his brothers, I only had about 11% coverage of Barsheba Tharp and John Robert Dyer. That 11% includes both of their DNA, so it’s possible that half of that or more comes from the Dyer side and not the Tharp side. What I actually found is that much of that DNA was from Barsheba Tharp’s father’s side – the Lewis Tharp line, and some of it I think comes from John Robert Dyer’s mother’s side, the Daughter/Taylor family.
As you can see in figure 2, by expanding my analysis to seven additional test takers (TT1-TT7), I was able to achieve 37.8% coverage of Barsheba Tharp and John Robert Dyer. This significantly increased the number of DNA matches I found that were relevant to my research question – the mother of Barsheba Tharp. The table below shows 16 matches I was able to find who descended from Joanna West’s grandparents, Humphrey Arnold and Harriett Smith and how they shared with different test takers in my project:
As you can see, in most cases, the Dyer brothers aren’t sharing as much DNA with the matches as TT4 and TT5 are. For example, Match P shares 49 cM with TT4, 16cM with TT5, 15cM with Dyer brother 2, and 14 cM with Dyer Brother 1. With just one of these data points, I wouldn’t have convincing evidence. But because four of my test takers share DNA with Match P, it’s a stronger case. In my research report, I also included a table similar to this showing DNA shared between my test takers who are descendants of Barsheba and descendants of John West and Bathsheba Arnold. These matches were harder to find, because there weren’t very many descendants of John West with Bathsheba Arnold. She died and he remarried, so I was able to find some matches through his second wife, but they are half cousins and share less DNA. I decided to expand my coverage of Joanna West by asking some of her descendants through Barsheba’s hypothesized sister, Elizabeth Tharp, to share their DNA match lists with me. I was able to get two more test takers to share. Figure 3 below shows the coverage of Joanna West’s genome.
Without TT8 and TT9, I would have had 18.9% coverage of Joanna West. With the addition of those two test takers, the coverage was increased to 21.3%. Those two test takers helped me strengthen the evidence of DNA matches to Joanna West’s parents, John West and Bathsheba Arnold, as shown in the table below.
This table shows that in the generation for Joanna’s parents, I needed many of my other test takers besides the Dyer brothers to strengthen the evidence. I also used the two new test takers, TT8 and TT9, descendants of Barsheba’s sister, Elizabeth Tharp, quite a bit. The matches were sharing anywhere from 8 cM to 32 cM and were either 5-6th cousins or half 5-6th cousins. The half 5-6th cousins were descendants through John West’s second wife, Sally Webb.
In my research report, I also included documentary evidence linking Barsheba Tharp to her mother, Joanna West, and Joanna to her parents John West and Bathsheba Arnold. Finally, I included documentary evidence of Bathsheba Arnold’s relationship to her parents, Humphrey Arnold and Harriett Ann Smith. I haven’t found evidence of Harriett Ann Smith’s name being anything other than Ann, or her maiden name being Smith, but hopefully more research will help determine why many people have Humphrey Arnold’s wife name as Harriet Ann Smith.
The evidence for Barsheba Tharp’s link to parents was scant, and that’s why I had to do a proof argument using DNA. Luckily the evidence of Joanna West’s relationship to parents was much clearer. Her father granted permission for her to marry Lewis Tharp, as shown in the marriage bond below.2
For Joanna West’s relationship to her mother, I needed to show evidence that John West was married to Bathsheba Arnold at the time of Joanna’s birth. I estimated Joanna’s birth based on her needing her father’s consent to wed in 1805 and the estimate that she was over 16 when she got married. That put her birth year range at about 1784-1789. I found a 1792 deed stating that John West and Bathsheba, his wife, were heirs of Humphrey Arnold, deceased.3
These key documents, along with additional documentary evidence, linked Joanna West to her parents, John West and Bathsheba Arnold, and grandparents, Humphrey Arnold and Harriett Smith. The DNA matches of Barsheba’s descendants to these ancestral couples ties the case of Barsheba’s mother together! Now I’m certain that Joanna West was the mother of Barsheba Tharp. My next phase of research will be to document the lines of descent from the common ancestral couples to each of the DNA matches.
You may be wondering – how I got people to share their DNA with me? Or was it targeted testing? The only people I target tested were my father-in-law and his two brothers. The others were DNA matches in the AncestryDNA database who I reached out to and asked them to share their match lists with me. I sent them a link to this Ancestry help article so they know how to do it: https://support.ancestry.com/s/article/Sharing-AncestryDNA-Results. If you are working on a research goal that involves their ancestors, I’ve found that many people are willing to share their DNA results with me as a viewer or collaborator.
I hope this example helped you see how expanding the coverage of your research subject you can help you find relevant matches and solve research questions that are further back in time.
- Nicole Dyer, “Connected DNA: The Power of Network Graphs” 17 December 2019, Family Locket (https://familylocket.com/connected-dna-the-power-of-network-graphs/).
- Fauquier County, Virginia, Marriage Bonds and Returns 2:370, Tharp-West marriage bond, 14 Jan 1805; images online, FamilySearch (https://www.familysearch.org/ark:/61903/3:1:3QS7-L9XF-6BPB : accessed 18 Aug 2020), DGS 7578972, image 451 of 688; FHL microfilm # 31633.
- Fauquier County, Deeds 13:338-341, Isaac Arnold et al. to Samuel Fisher, 10 July 1792, recorded 27 Feb 1797; image online, FamilySearch (https://www.familysearch.org/ark:/61903/3:1:3Q9M-CSKJ-MSTV-2 : accessed 3 May 2022); DGS 008151658, image 423 of 526.