Thursday, December 13, 2012
I'm not one to push any particular company or commercial venture, but sitting here in mid-December it would be remiss of me not to mention to a group of people interested in genealogy that if you were ever considering getting your DNA tested, or were looking for an unusual gift for anyone else, now's the time. At least two of the major DNA testing companies - Family Tree DNA and 23andMe, have significant sales going on. The third major DNA tester - Ancestry.com, has offers out as well; I just couldn't tell if they were having a sale when I checked.
If you want to know what it's all about, just type "genetic genealogy" or "genealogy DNA testing" into your favorite search engine; there really are a ton of helpful sites out there now to explain it all. But to start you off, here's my amateur's explanation:
There are three main types of DNA being tested: one is autosomal DNA, which covers all the DNA you got from all your ancestors but can only give you general percentages of how many of your ancestors were from what ethnic backgrounds... interesting if you think you have certain ethnic heritages, but it won't help you with who specifically your ancestors were. Then there is mitochondrial DNA, a very specific piece of DNA both men and women get from their mothers, which gives you very general information on your mother's mother's mother's mother's mother's mother's... you get the idea. Interesting but again it won't lock in specific ancestors. Finally, there is y-DNA - the Y chromosome that men inherit from their fathers, and women don't have. Since traditionally family surnames were passed down through males in Western society, this is the DNA most often studied for genealogy; but it only tells you about your direct male ancestry (your father's father's father's father's father's father's... yeah I know, you get the idea).
There are two types of y-DNA testing: most test anywhere from 12 to 111 "STRs", which are a combination of markers on the Y-chromosome. Think of it as if every father told their sons the same story, and usually the sons remembered the story exactly, but very rarely one son got a word wrong here or there and passed it on that way to his own sons. With billions of fathers and sons over many generations, the stories remembered by each male living today would be very different. STR testing pulls your version of the story out of your DNA, and by comparing it to others you can tell whose stories are closest to yours and therefore who is closest to you (through male ancestry, at least) on the great family tree that connects us all.
The other type of y-DNA testing is SNP testing, which finds specific mutations in your DNA that tie you back to older groups of humans. Mapping SNP migrations is an on-going activity that one day may show us the exact path our male ancestors took across the globe, but for now can usually only barely reach about 1000 years ago when surnames first started. Many of the debates though are VERY interesting... this is a science being born as we speak.
How does this all help our search for ancestors? Well, apart from the general "gee whiz" factor of knowing something about your most distant ancestors, DNA testing can only give you hints unless someone else closely related to you has more historical research you can connect to. Just as an example, I have tested my STR markers and found that my Vance ancestors are connected to a number of other Vance immigrant lines to the United States. The group is called "Group 2" by the Vance/Vans/Wentz Y-DNA surname project. My Vance line is known to have come from northern Ireland, and a couple of the other descendants have traced their lines to Ireland also, so we know we're all connected to Vances that lived there around 1600-1700, and that we are more closely related to each other than we are to other Vances. Beyond that, we don't yet know how our family trees connect. But at least we all know we're working on the same puzzle.
So bear in mind that DNA testing won't (yet) tell you exactly who your ancestors were, or break through that brick wall to find where in the "old country" your Vance or Wentz ancestor was born, etc. And you should also know some people have found adoptions in their family histories through DNA testing, so you need to be prepared for a possible surprise (I should note NONE of this does anything close to paternity testing).
But the other advantage of DNA testing is that as the science evolves, you will continue to find out more and more about your own ancestry; both facts that can be verified through traditional genealogy, and facts that you could never hope to trace far enough back to learn. It can be a fascinating parallel study to your historical record research. If you were ever considering joining in, or getting additional tests done, this may be the cheapest time in awhile to do it - but act fast!