The August 20^th blog posting described a discovery made while my friend M.J. and I were trying to confirm the name of her maternal grandfather (i.e., her mother's biological father). My tale was simply a coincidental side story. This posting is about a closer analysis of the DNA.

My initial purpose in building an Ancestry family tree was to explain relationships, and I was able to identify and place 13 individuals who were M.J.’s close DNA matches. The results pointed to a man we’re calling “Grandpa X.”  A summary (with names sanitized) is shown in these tables:

Lois Abromitis Mackin—who regularly writes a DNA column for IGSI’s journal, The Septs—gave valuable advice and nudged me toward a DNApainter tool called “What are the odds?” (WATO).

WATO computes the probability of where an individual might fit into a known family tree by using the amount of DNA shared. Here’s what one needs to get started:

1. An account at DNApainter.com (basic version is free)
2. Autosomal DNA test results
3. A target DNA match 
4. A research question or hypothesis

I could have manually entered the summary information from my tables into WATO. However since I’d already created an Ancestry tree, I uploaded the gedcom file. Then I entered the shared centimorgans for the 13 matches.

Again, because I want to maintain the privacy of everyone involved, I’m not sharing the actual WATO tree image here. Suffice to give you the conclusion: “Grandpa X” is 61 times more likely to be M.J.’s grandfather than any other individual on the WATO tree.

P.S. Are you interested in reading Lois Mackin's previously-published DNA articles? If you're currently an IGSI member, you can review "Contents" of past issues of The Septs and download the PDF for easy reading. Start by logging in as a member and clicking on The Septs (Journal) at left.