Author Archives: dnasleuth

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.

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Triangulation with GEDmatch

On 25 Mar 2017, the Central Indiana DNA Interest Group is giving an in-depth presentation on the valuable (and mostly free!) DNA tools at GEDmatch.

At this program, we’ll be talking about the benefits of GEDmatch and walking through how to use the site. Of course, the most Basic perk of GEDmatch is that you can compare DNA from people who tested across different platforms (companies). On an Intermediate level, GEDmatch has tools to help you sort your matches into different lines of your family tree. For participants open to dipping their toes into Advanced territory, we’ll talk a bit about * triangulation *.

I know when I attend webinars or presentations, sometimes my brain gets full and doesn’t process everything I just heard. Then it’s helpful to have a resource to revisit later to help the more complex material sink in. So I thought I’d post something about * triangulation * on my blog this month!

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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.

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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.’

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