Barton Lewis's Genealogy Pages

Brick wall case study no. 2

On another page at this site, I talked about how I solved my great-grandmother's NPE using DNA. I also broke down a brick wall on her maternal side: that of her grandfather, Nathan Montgomery. In this case, I was helped by having 4 different sets of matches on my mom's and uncle's chromosomes to prove Nathan Montgomery's parentage. As in the previous case study, I was also fortunate to discover previously unknown (to me) documentary evidence to support my findings.

My 3rd great grandfather, Nathan Montgomery, was born in Virginia in 1813. By 1840, he was living in Walker County, Alabama. Nathan's wife, Martha Caroline, was said to be the daughter of Andrew Nelson, who was living with them in the 1850 census. (Other evidence - including DNA - suggests Martha was Andrew's granddaughter. See a future case study on this site.) Nathan's and Martha Caroline's oldest child, Alexander, was born in Indiana in 1832.

I found Andrew Nelson living alongside John, Michael, and Alexander Montgomery in Parke County, Indiana, in the 1830 census. I didn't expect to find Nathan as a head of household since he was only 17, but neither did I find a male 15-20 in any of these 3 households. For the moment, I was stumped.

Then I got my mother's, aunt's and uncle's DNA results back from FTDNA. They all matched 3 brothers and a 1st cousin, descendants of one Margaret Montgomery. Margaret's father was John Montgomery, the same John Montgomery living alongside Andrew Nelson in the 1830 census. Tim, the contact for the group, noted that Nathan named a son John Walker Montgomery and speculated that Nathan was a grandson or great-grandson of Alexander Montgomery and Martha Walker, John's parents. But with no solid evidence, it was just that - speculation.

In the meantime, I began looking at the other matches on the chromosomes where Tim's father, uncles and their cousin matched my kits. I soon discovered that there were multiple descendants of John Walker and Ann Houston, the common ancestors for the most distantly related of all these matches, with more recent common ancestors for others. Following is a breakdown of the 4 match sets and below that a tree which shows how everyone is related.

Chromosome 4, part 1

Brothers Paul and Raymond and their cousin, Charles, match my mother on chromosome 4 from 40-66 Mbp for 19 cM. Also matching there is Suzanne, a descendant of Margaret Montgomery's brother, John, Jr., and Benjamin, a descendant of Margaret Montgomery's uncle, John Walker Porter.

chr 4-1_CB chr_4-1_table chr_4_table

Chromosome 4, part 2

Picking up where the prior segment left off is James, a descendant of another John Montgomery, Margaret Montgomery's nephew. James matches my mother from 66-82 Mbp for 13 cM and then again from 127-146 Mbp for 16 cM. Matching my mother for 61 cM is Juanita, her 2nd cousin, and Thelma, for 12 cM; like Suzanne, Thelma is a descendant of John Montgomery, Jr., Margaret Montgomery's brother, but from a different child.

chr_4-2_CB chr_4-2_table chr_4_table

Chromosome 6

In my uncle's kit on chromosome 6, Melvin overlaps with Stephen and Juanita on smaller segments; Melvin is Paul and Raymond's brother, and Stephen is a descendant of Margaret Montgomery's aunt, Katherine Porter.

chr_6_cb chr_6_list chr_6_table

Chromosome 21

On chromosome 21, Juanita's nephew, Norman, matches my uncle on 2 segments: from 14-19 Mbp and 21-38 Mbp. Overlapping him there is Suzanne and Charles; and Travis, like Thelma and Suzanne, a descendant of Margaret Montgomery's brother, John, but through a different child.

chr_21_chr chr_21_list chr_21_table

These above relationships are shown in the table below (the matches are color coded by chromosome - see the key below the table; some appear on 2 chromosomes and so both colors are reflected in the name):


Declaration of Susannah Mills for a pension based on her father's Revolutionary War service, 1845, Peoria, Illinois, naming her brother, Alexander, and his children, including Nathaniel.

Documentary evidence

At about the same that I discovered these autoso­mal matches, I made the ac­quain­tance of Kenneth Mont­gomery, a descendant of Nathan's and Martha Caroline's through their son John Walker Mont­gomery. Kenneth tested his Y-DNA and was a 64/67 match with Thomas Mont­gomery, Thel­ma's broth­er. Kenneth also shared with me the affi­davit of Susannah Mills, daughter of John Mont­gomery and Susan­nah Porter, in which she gave a very detailed account of her family. Listed as her parents' 3rd child was "Alexander (who married Barbara Harris, and died in Franklin County, Indiana, leaving for heirs – 1st Elisabeth Montgomery – 2nd Susannah Montgomery decd – 3rd Nathaniel – 4th John – 5th Samuel Walker – 6th William – 7th Jane – 8th Margaret) ..." Shortly thereafter, I discovered the biographical sketch of Samuel Walker Montgomery, which named his parents, Alexander Montgomery and Barbara Harris, and stated his father died in Franklin County, Indiana in the Fall of 1822. The sketch names Samuel's siblings, including "Lincoln, who resides in Alabama." All of the other names are identical to those that appear in Susannah Mills's declaration. It seems reasonable to conclude that Nathan(iel) Montgomery had the middle name Lincoln, as he was living in Alabama when his brother's sketch was written, and that he named his first child, Alexander, after his father. (As previously noted, Nathan named another son John Walker Montgomery – additional evidence of this connection.) Finally, I discovered Barbara (Harris) Montgomery living in Fountain County, Indiana, in the 1830 census. In addition to 3 other children, there is a male 15-19 in her household - presumably Nathan, living in the county adjoining Andrew Nelson and his paternal grandfather, John Montgomery (Susannah died about 1802).


This case study illustrates how a set of interlocking matches add up to a sum that is greater than its parts. Not everyone is matching everyone else, but people are matching in ways that suggest they are part of a common lineage. Suzanne and Charles match both on chromosomes 4 and 21; my mother and uncle match everyone on segments they inherited from their paternal grandmother (I know this because I have mapped their chromosomes to their 4 grandparents); and Juanita, their 2nd cousin, matches both groups that are not in common with Suzanne and Charles.

This example also illustrates how DNA and documentary evidence work together. I wouldn’t be comfortable stating Nathan Montgomery was the son of Alexander Montgomery and Barbara Harris with just the DNA or documentary evidence alone. With just the DNA, I might be tempted to state that Nathan fit into the family, without knowing exactly how. He could have been a grandson of John Montgomery and Susannah Porter, but I would not know through which of their sons; or a great-grandson of Alexander Montgomery and Martha Walker, but through which son, again I would not know. With just the documentary evidence, I might be uncomfortable stating that Nathan was part of this family at all. The Nathaniel named in Susannah Mills's affidavit could be a different Nathan(iel) Montgomery - but the DNA narrows the chances; likewise, there would be less basis for identifying Lincoln Montgomery as Nathan without the DNA supporting the circumstantial evidence.

For the first two case studies I chose examples where genealogical mysteries were solved by both strong DNA and documentary evidence, working together. The next example introduces questions that arise when a TG is formed by a distant ancestor for all of the matches, and a much nearer MRCA for some.

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