This “Tip of the Week” was in a recent email newsletter from Family Tree Magazine, but I can’t find it posted anywhere online, so I am posting it here so that I can share it. It has some very good information about using DNA evidence to break down a brick wall, and the differences in DNA testing for genealogical purposes.
Tip of the Week: Solving Genealogy Problems With DNA
See how one family is using genetic genealogy testing to chip away at a longstanding brick wall: the identities of their great-great-granparents. This is the type of research problem you can learn to resolve through our Genetic Genealogy 101 Family Tree University course, running Oct. 20-Nov. 14:
- The question: Helen Johnson was born March 2, 1889, in upstate New York. Her birth certificate lists her father as unknown. Her mother is named, but genealogy research has revealed little about her. Helen married into the final of three families to adopt her. Although she lived a long and content life, she never knew who her biological parents were.
- The tests: Helen had a son and a daughter, each of whom had at least one child. Helen’s daughter inherited her mother’s mtDNA and passed it on to her son. This grandson took an mtDNA test in hopes of finding a match, but none have been found.
Next, the family turned to autosomal DNA. Each of Helen’s children inherited half of their autosomal DNA from their mother. Each of Helen’s grandchildren inherited approximately 25 percent of Helen’s DNA. Two male grandchildren, one from each of Helen’s children, underwent autosomal DNA testing. A person matching both grandsons would suggest all three are related through either Helen or her husband. If the family tested just one grandchild, or two grandchildren who are siblings, a match might be related through the grandchild’s other parent, instead of through Helen’s line.
- The result: Helen’s grandsons are indeed first cousins, sharing slightly less than 12.5 percent of their DNA. The testing company’s database contains matches to both, including some estimated to be third cousins.
The two cousins have determined that one match is related through Helen’s husband. They’re continuing to work with matches and do research to narrow down who Helen’s parents might be. Also, a match to the initial mtDNA test still might turn up.
The family actually has a website regarding this project, which you can find HERE.