The Unknowns by Maureen Culbert and Megan I. Culbert
DNA Testing in Genealogy: Both a Starting Point and a Helpful Tool
Some of you may have thought about getting—or have already received as a gift for the holidays—a DNA test kit from Ancestry, 23andMe, or another company such as Family Tree DNA, and are now wondering what to do next. If you would like to buy one and haven’t yet done so, the holidays are the best time, next to Father’s and Mother’s days, when test companies offer the best sales. It really depends on how far you have gone in your research, where you are stuck and therefore prevented from going back any further, and if you need additional help that DNA and other people’s online family trees can offer.
An understanding of which DNA tests these companies offer, and what kind of information those tests yield, is important before purchasing and taking a DNA test. It is also important for consumers to read and understand test companies’ privacy statements and terms and conditions. Additionally, some companies and third-party websites require an opt-in or opt-out for allowing law enforcement to compare DNA samples of perpetrators of particular serious crimes to samples within the companies’ databases, and it is important for test takers to understand how their DNA may be used if they opt in or out. Taking a DNA test can also yield unexpected, surprising and even shocking results. It is important for each test taker to be able to provide informed consent to a DNA test; this includes knowing that their test results may reveal family secrets that may be upsetting to some people, including living relatives.
Most DNA testing companies include two major components: some form of genetic relative matching and some form of ethnicity estimates. For genetic relative matching, the test companies analyze your DNA sample and compare it to the other samples within their database. They are then able to list your genetic relatives who have tested with that particular test company. (Some testing companies and other third-party websites also allow you to upload your DNA test results from other test companies onto their websites, so you have even more opportunity to find genetic relatives.) Test companies also provide the amount of DNA you share with each DNA match, which can help you narrow down how you might be related to one another.
User-uploaded family trees on DNA test companies’ websites can also help with determining how you are related to a genetic match, though they can contain mistakes or wrong information entirely. Not everything that people post in their online family trees turns out to be accurate, but they can often indicate a good starting point, if researched and cited well. One should always look at the sources cited, and the information therein, and evaluate them for yourself. (Just because someone had the same name as your ancestor and lived in the same city does not mean that every document you find with that name in that city refers to your ancestor, for instance.) Non-paternity events or NPE due to illegitimacy, adoption, etc., can also complicate matters. One should use a combination of DNA testing and traditional genealogical research to get the best and most accurate results.
Ethnicity estimates are a bit more complicated. They are, first of all, only estimates, and not written in stone. They are not an exact science, and although they can be helpful (and fun to see), they should always be coupled with traditional genealogical research before drawing any conclusions. Test companies compare your DNA sample to those taken from various reference populations around the world: living people whose ancestors have lived in a particular region for several generations. The test companies then estimate where your ancestors may have originated in the past few hundred years based on how much DNA you may have in common with these particular reference populations. However, many border changes in the past few hundred years (and other factors) mean that the results are really only accurate to the continent level, and sometimes to more specific regions, but generally not to specific countries. Your ethnicity results are updated periodically as more people have their DNA tested and as the technology improves.
DNA testing for genealogical purposes can be complicated to understand at first, but it can be a useful (and fun) tool for genealogy.
Maureen Culbert is vice president of the Springfield Historical Society. Her daughter Megan, who contributed to this column, works at Fenimore Art Museum.