Category Archives: basics

Negative Evidence: genealogy methodology and DNA

Genetic genealogy, like documentary genealogy, can result in negative findings and negative evidence. What’s the difference? (It wasn’t that long ago that I was confused about that too!)

You start with a research question and a source. ‘Negative’ means the information you’re looking for in the source isn’t found. A negative finding doesn’t help you answer your research question. Negative evidence does. You may have to understand the context to know which one you have. Some examples, with document-source genealogy and DNA-source genealogy, may help.

Continue reading

Using cM counts to help find the common ancestor: part 3 of 3

What if your analysis of your match doesn’t match the shared cM chart?

Most people are able to find their Most Recent Common Ancestor (MRCA) when they share over 90 cM of matching DNA. Below that, it begins to get a little more challenging. In this February 2017 series of blog posts, I’ve been focusing on identifying the MRCA with people who share more than 60 cM with us, projected to be 4th cousins or closer. You may not have much in that range and have chosen to work with matches who share 45-60 cM with you. That’s okay. There are a few key reasons why we want to focus on this group.

Continue reading

Using shared cM counts to help find the common ancestor: part 1 of 3

Last month I suggested that soon I’d be sharing some results of a citizen science DNA project I’m working on. However, I realize now that the proposed blog draft is too long, with too many diversions to explain some basics that might help newer readers.

So I’m taking a step back and planning several short posts first. The theme is ‘Using shared cM counts to help find the common ancestor.’

Continue reading