Friday, January 22, 2016

Genes Day Friday - What I have learned so far through DNA testing

I thought it would be fun to recap some of the things I have learned genetic genealogy and DNA testing. Let me begin by saying THANK YOU! to the dozen or so relatives that have spit and swabbed for me. None of these breakthroughs would have been possible without your help.

1. Genetic genealogy and paper genealogy are in some ways very opposite. In paper genealogy, you start with a known person, and work outward from there, painstakingly creating family groups and pedigrees by searching through the records left behind by ancestors, friends, associates, and neighbors. You connect to people through chance and happenstance as often as known connections. In genetic genealogy, you are connected to other testees by the scientific confirmation of shared DNA, proving a blood link to that person. Sometimes (hopefully often) you can use paper genealogy to determine where and how that link was made. Sometimes you can't, and you're just stuck knowing that somehow you are related to that person.

2. Sometimes genetic genealogy helps you break through brick walls that would otherwise be impossible to penetrate. This was the case in my Grandma Blossom's maternal line. DNA testing led me to a relative who not only lives in Europe, but was intimately familiar with the area, history, and people. Within a few short weeks, he helped me put together nearly 300 years of family history for my great-great-grandmother Maria (Zitzmann) Hoffman, when I had long assumed I'd never get beyond her.

3. Sometimes you uncover things you never expected were there. Such was the case when I found out one of my ancestors was not James Harris, but in fact was William Vadnais. This discovery changed a significant portion of my genetic family tree, and has taught me to never assume that everyone listed in the paper trail is actually my ancestor by blood.

4. Everyone has two family trees - one that's genetic, and one that's genealogical. CeCe Moore taught me this. Not all of your paper ancestors will appear in your DNA - you only get half of each parent, who only got half of their parents, who only got half of their parents, etc. Within a few generations, ancestors will drop out of your genetic family tree because their DNA was simply not passed on to the next generation. That doesn't mean they aren't your ancestors though, just that they aren't represented in your DNA. Likewise, my paper family tree still includes Jim Harris because he raised that ancestor of mine and put his name on her birth certificate, even if he wasn't her biological father. His life and his family history influenced the way he raised my ancestor, so knowing about his family tree is just as important as knowing about the biological tree of William Vadnais.

5. You learn funky new words and acronyms like SNP, haplogroup, STR, endogamy, and centiMorgan. It's like learning a new language, but in learning it you learn how to discuss your family history in a whole new way. Not only do you think in terms of shared ancestors, you come to think of how much DNA you likely share with that 1C1R, or where your paternal ancestry comes from not just 3 or 4 generations ago, but hundreds of years before records were kept. It's fascinating and difficult, and I love it.

6. And the most particular thing I've learned over the last couple weeks - just because you share a certain percentage of DNA, that doesn't mean you can tell right off how closely you're related to them. If you trace your lines back far enough, you'll start to see some ancestors popping up in multiple places on your family tree. That's called ancestor collapse - being descended from the same person or couple through multiple lines of descent. This affects how much DNA you share with someone, because if you and your match have the same ancestor, but if one or both of you have multiple lines of descent from that someone, their DNA will be over-represented in your genome. You'll share more DNA than you would if you only had one line of descent from that individual, so it'll look like you're more closely related than you actually are. For example, if you're doing genetic genealogy on your French-Canadian lines, you really do need to push the lines back as far as you can because there was a lot intermarrying of families, which leads to having some ancestors pop up more than once in your family tree. That's something you need to know if you're going to try and pin down common ancestors with your DNA matches.

Have you thought about taking a DNA test to help you in your research? Or have you taken one already? What have you learned from it? Leave me a comment!

1 comment:

Jana Iverson Last said...


I want to let you know that your blog is listed in today's Fab Finds post at

Have a great weekend!