Analyzing a DNA Match

Last August, an new, unknown DNA match appeared on my husband's AND my mother-in-law's FamilyTreeDNA results with enough shared DNA that I thought I should be able to figure out the relationship.

For the screenshots below, I am narrowed down the results by searching on their common surname (which I am keeping private).

My husband's results:

His mother's results:

This results page shows that they both share a good bit of DNA (shared Centimorgans and Longest Block) with Mr. K and his daughter H.K.

Mr. K and his daughter, H.K. both share a little bit more total DNA with my husband than with his mother. Note that this is endogamy at work: shared Jewish DNA. I find that looking at the longest block (largest DNA segment) is a better way to confirm a relationship; with a longest block of 38 cM or more, that will not be due to endogamy and I should be able to make a good effort at finding the relationship.

You will also see that Maternal (2) appears in both results. This is because I have set up a family tree for both my husband and his mother and I have linked some family members' DNA to individuals in the tree. This helps to narrow down DNA match results (also known as phasing) to an individual's maternal or paternal DNA.

The circled relationships indicate that I have linked Mr. K and his daughter H.K. to the trees of my husband and my mother-in-law.

Under the Ancestral Surnames heading the surname of Segal immediately jumped out at me, as that is my husband's great-grandmother's surname. The surname Dlugatch also looked familiar, and at first, I couldn't quite place it.

The next thing to do is to look at the chromosome browser. (Note that AncestryDNA does not have a chromosome browser and although its shared matches feature is pretty cool, sometimes it's helpful to look at where a match is located. AncestryDNA testers can transfer their raw data to FamilyTreeDNA for a small fee or can transfer to GEDmatch for free.

Husband's chromosome browser with Mr. K (in orange) and his daughter H.K. (in blue):

Husband's mother's chromosome browser with Mr. K (in orange) and his daughter H.K. (in blue):

The images show chromosomes 1 through 4 for each. The orange areas represent the DNA segments where the tester matches Mr. K. The light blue areas represent the DNA segments where the tester matches H.K. Chromosome 3 is where the largest segment match is.

In the next post, I will share how my mother-in-law is a second cousin to Mr. K., and my husband is a third cousin to his daughter, H.K.