The Shared cM Project is a collaborative research project that uses data from 100s of genealogists to generate shared DNA ranges and averages for nearly 50 different genealogical relationships. The most recent version of the Shared cM Project, Version 4.0, was released on March 27, 2020 (I had so much free time in the early days of the pandemic!). See “Version 4.0! March 2020 Update to the Shared cM Project!” Keep those submissions coming, I’m hoping to do an update in 2023!
One of the enhancements to the Shared cM Project that has been on our minds since the creation of the project is the use of siblings and/or same-generation cousins to narrow down the list of possible relationships to a DNA match.
For example, my sister and are full siblings, and thus by definition we have the same genealogical relationship to all of our genealogical cousins. Sometimes this can be a challenging concept! This graphic shows how my sister (Sibling #1) and I (Sibling #2) have exactly the same genealogical relationship to this third cousin (3C):