As I work on developing my own best practices of using DNApainter and inferred matching, I’m amused at how variable the results are. Here’s some of my results as I work through my matches via my paternal side. All three matches are 2nd Cousins, once removed, all great-grandchildren of my grandfather’s sister.
This is why testing multiple family members is a good idea. Because for each segment my brother has that I don’t, I can POTENTIALLY infer that I got that area of DNA from my paternal grandmother instead of my paternal grandfather, who was the brother of these cousins’ ancestor. (If any of this “non-matching” DNA matches any of my previously painted paternal grandfather’s DNA, well obviously, that’s where it belongs.)
My sons’ DNA helps verify that there are not any errors in my matches, as all their DNA on this line SHOULD be via me, and we’ve already identified some gaps in my direct matching. This is one of the benefits of inferred painting over direct painting. My mom is included as a standard measure to ensure there is not descent via both paternal and maternal chromosomes.
This is also why there are a range of potential cMs shared for any particular relationship. A very useful tool is DNApainter’s Shared cM Project, in which you input a shared cM number, and it will suggest the most likely relationships. In some cases, there are a LOT of potential relationships. Their tool reports both in numbers, and with a visual graphic, so should appeal to all type of learners.
For these three cousins, my top result included the relationship I’ve proven via paper genealogy, so those relationships fit the “typical” amount of shared cMs. The following chart shows all our percentage results. It is interesting that although I’M perfectly typical, my son’s inherited cMs are not.
| Cousin 1 | Cousin 2 | Cousin 3 | |
| Self | 1st group | 1st group | 1st group |
| 53.16% | 48.26% | 44.68% | |
| Brother | 2nd group | 1st group | 1st group |
| 29.46% | 38.65% | 38.89% | |
| Son D | 4th group | 1st group | 2nd group |
| 16.23% | 30.19% | 29.19% | |
| Son N | 4th group | 4th group | 4th group |
| 16.69% | 8.60% | 14.95% |
The most important take-away here is that, at the more distant relationships, you have to be willing to consider the RANGE of potential relationships which are statistically possible. You can learn more from the DNA Geek.
Historical Pursuits 