You know how it is – you look in your DNA match list and see an entry for someone you don’t know. There are a few steps you can take to discover the relationship you share. The amount of DNA you and your match share is listed in centimorgans (cM). The cM amount can point you in the right direction to discern your relationship. The DNA company estimates a relationship, but you need to figure out where the person fits in your family tree. If you can correctly place a DNA match in your family tree and determine which ancestor or ancestral couple you and your DNA match both share, you can verify that you are genetically related to that ancestor.
The Shared cM Project 4.0 tool v4 (https://dnapainter.com/tools/sharedcmv4) shows a list of many relationships. After the amount of DNA shared with a DNA match is entered, a list opens that shows family relationships and the probability that you may share a specific with a DNA match. To learn more about the Shared cM Project Tool, read my blog post, The Shared cM Project Tool on DNA Painter.
There are different ways of diagramming family relationships. I’ll highlight some charts that may help solidify the concepts of cousins and once or three times removed in your mind. You may also be interested in using the diagrams to help you explain your research to your family or clients.
Cousin Calculator Chart
The best-case scenario occurs when a DNA match has a family tree connected with their DNA profile. The family trees of DNA matches will help you identify ancestors that you and your DNA matches share. If you find an ancestor that you recognize in a DNA match’s family tree, use the Cousin Calculator chart found at the FamilySearch Blog to determine the relationship between you and the DNA match. A preview is shown below.
Jessica Grimaud, “What Is a Second Cousin?: How to Calculate Family Relationships,” FamilySearch Blog, 23 July 2019 (https://www.familysearch.org/blog/en/what-is-a-second-cousin/ : accessed 20 March 2021).
To use this chart, imagine that your ancestors are listed along the top of the chart, and your DNA match’s ancestors are shown along the left side. Choose the relationship you have with the shared ancestor and highlight it in some way. You could handwrite the ancestor’s name on the chart, or if you are working on a computer, add a text box and type the ancestor’s name in it.
Next, look at your DNA match’s family tree, either count the number of generations or label the relationships as you count up the generations by identifying DNA match, parent, grandparent, great-grandparent, etc., until you reach the shared ancestor. Then find the intersection of the two grandparent relationships by tracing down from your ancestor and across from your DNA match’s ancestor.
In this case, the DNA tester’s 2nd great-grandparent is the same person as their DNA match’s great-grandparent.
How Many Centimorgans Do You Share with Your Relatives?
Another chart that may be helpful is “How Many Centimorgans Do You Share with Your Relatives?” at the FamilySearch Blog. A preview is shown below:
Annelie Hansen, “Untangling the Centimorgans on Your DNA Test,” FamilySearch Blog, 6 April 2020 (https://www.familysearch.org/blog/en/centimorgan-chart-understanding-dna/ : accessed 20 March 2021).
I like the way this chart illustrates relatives and how they connect to your ancestors. I added updated ranges of observed DNA in specific relationships from the Shared cM Project 4.0 tool v4. Try these charts to help you visualize relationships in a way that will help you make more progress in your family history research and reach your goals.
Best wishes in your research!
To learn more about using DNA in your family history research, read our new book, Research Like a Pro with DNA – A Genealogists Guide to Finding and Confirming Ancestors with DNA Evidence, Kindle Edition.