The past few weeks have been pretty hard on genetic genealogy (DNA testing). First, a professor of evolutionary genetics came out strongly against genetic genealogy, calling it "genetic astrology". Next one of the testing companies was accused of making exaggerated claims at a genetics conference. And then a widely-publicized "consumer report" was issued slamming DNA testing and the companies and their claims.
Debate still rages around the Internet about the value of these warnings, but most of the cooler heads seem to agree that the extreme positions are unwarranted; that DNA testing for genealogy can be very useful but people should have realistic expectations - and yes, some testing companies have made exaggerated claims. So I thought I would post my own experience of what people should expect that DNA testing can and can't do for them.
What it CAN do:
1. The best value – by far – of any DNA test is that it can match your DNA to others who may already know more about your common ancestors. An autosomal test could find a second cousin who knows who your biological parent was. A Y-DNA test could connect you to someone with a documented 400-year old family tree. This is mostly luck and depends on others testing and available historical data, not just DNA. But you might never know you were connected to those people and that research if you didn’t take the test. I include here the connections you can make to the projects that collect and analyze what is known about people with related types of DNA to help them as a group learn more about their origins - for instance, the Vance/Vans/Wentz Y-DNA Project is a great example of group knowledge you can connect to.
2. A Y-DNA (and to some extent a mtDNA) test can estimate for any two tested people how long ago their common ancestor lived (but still with a fairly wide margin of error, so it can’t tell you who that common ancestor was).
3. Any DNA test can identify general geographical areas where people with your DNA are believed to have lived. But there are limitations. Y-DNA and mtDNA tests identify your haplogroups which reveal the migrations of your ancestors thousands of years ago (many years before your family tree). Autosomal testing identifies general areas for your more recent ancestors – areas as wide as “British Isles”, or “Eastern European”; nothing more specific, and it won’t say which ancestors or when or for how long they lived there.
4. A DNA test can tell you what countries today have the highest number of tested people that most closely match your DNA. That could be useful as a general indicator of what part of the world your ancestors came from. Or it could just be a coincidence if someone from a branch way back in your family tree moved there and had a particularly large number of descendants.
5. A DNA test can put you in a group that will continue to grow as more people are tested, and whose story will continue to grow with each test. It may take months or years, but our knowledge of our ancestry will continue to evolve as the information and knowledge grows.
What it CAN’T do, unless you luck into a match with someone who has that information already:
1. By itself a DNA test can’t name your ancestors, and it won’t add people to your family tree.
2. Although some testing companies like 23andMe can give you medical information based on your DNA, the test can’t tell you which of your ancestors had those medical conditions. Or where you inherited your red hair, blue eyes, or webbed toes from.
3. It can’t tell you that your ancestors were Vikings, Celts, Romans, Normans, what tribe of Indians they were from, or how you personally connect to any other historical group of people. Actually the experts can theorize that close matches to your DNA existed, say, among the Vikings, either through modern analysis or because they tested old bones. But people intermixed so much throughout history that all those groups were made up of many kinds of DNA, and that’s still no evidence that YOU personally descended from one group and not another. Any identification with a historical group is based on a general theory, not from anything they discovered in your DNA.
4. It can’t tell you that you’re descended from royalty or any historical figure, although groups who already believe they do try very hard to claim it’s proven when the DNA shows they all really ARE a close match to each other. It’s still the historical research that proves the lineage, not the DNA. You don’t have proof through DNA unless you dig the ancestors up. Even if you match a known descendant of Prince Eduardo the Magnificent, your ancestor might have been his third cousin Fergus the Drooler.
5. And finally, a DNA test only tests part of your family tree, because even an autosomal test only gathers data from pieces of your total DNA and anyway you have many more ancestors than sections of DNA so many of your ancestors aren't reflected in your DNA at all. So be prepared that the test may show a different ancestry than the one you thought you had. You may still be right.
So... is it worth testing? Only you can answer that. But I still thought it was and I learned many interesting things from my tests and connected with many people who share my interests and research. Just be sure you know what you're getting into before you test.