Genetic Testing for Genealogy Uses

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You can’t throw a stone without hitting a genealogist who is using DNA testing to further their research (trust me, I’ve tried). When it comes to testing ourselves, it’s easy to take the plunge blindly. For every person I talk to that took the tests and uses them effectively, there are ten that have no idea how to even read their results. And getting family to test? Oy. How do you get someone to give you their bodily fluids that doesn’t involve… less than ideal tactics? What if they have questions? What if you have questions?


What To Test
The first thing you need to know is there are three kinds of DNA tests available direct to consumer. The first and oldest is the Y chromosome test. This test is for men only and traces the direct paternal line back through time. Depending on the test level chosen, this one is accurate for matching to other men who have tested between 4 and 29 generations. Very cool if you think there might be a paternity issue in your family line or you don’t know your paternal line. Also cool if you just want to know where your male line migrated from since the beginning of time. Not cool if you need to know your father’s mother’s line……. she doesn’t have a Y chromosome!


The second test is the mitochondrial test (mtDNA). Mitochondria are passed from mother to children, so both genders can test, but it is limited to the direct maternal line. A son will have his mother’s mtDNA, but he won’t pass it on to his children. This is a great companion test to the Y chromosome test if you want to know your direct maternal line. However, because mitochondrial DNA doesn’t mutate as often as Y chromosome DNA, the accuracy isn’t there. Being an exact match can indicate a common ancestor lived hundreds if not thousands of years ago, rather than the more recent connection found in Y chromosome DNA.


While the first two tests are good tests, and I’ve had both done in my family, they are restricted to the direct lines. This leaves most of your ancestors out of the mix. Autosomal DNA is what you’ll want to get tested if you’re looking to find cousins or confirm ancestral lines. This tests the autosomal chromosomes, that’s 22 pairs of chromosomes, and the X chromosome. The X is passed down strangely, and has its own rules for matching. There’s a lot of resources already covering how to use that information and I’ll go so far as to shill for the Facebook Group Discussion Group as one such place to get into the real meat of chromosomes and understanding them better. For now, just know that autosomal chromosomes are a mix of your ancestors from all lines, so using their information will get you cousin matches from any ancestor in your tree. Autosomal tests will give you cousins that match you within 8 generations, most of whom will be in the 4th to 6th cousin range. This is the test we’re discussing today.


Where To Test
There are several companies that provide genetic testing. For genealogical purposes, you’ll have the choice of, FTDNA, or 23andMe. Each one has strengths and weaknesses, and which one you choose will depend on your end goals. I would recommend investigating the sites of each on your own and reading the Terms of Service. Know what you buy before you buy it. And if there is no great rush, wait for a sale! Now, if you’re hoping I’ll tell you which is the best, I just won’t do it. I will say I tested with two of the three and chose not to use the third as it presented no additional benefits. I will also warn you away from any other company than these three if your goal is to cousin match. National Geographic has a test that is super serious and helps researchers understand genetics better, but it has NO cousin matching at all. So if all you want is your ancestral origins and possible ethnicity makeup, spend money here and help the science. But your data is nontransferable and useless in any other goal. Also, avoid It’s not the Ancestry test and lots of people have confused it with the real test. Sadly, the results are nontransferable and useless for cousin matching. This one is often seen on Groupon’s site and looks like a really great deal for DNA testing. It’s not.


What You Get
There are some basic differences between the three sites and your ultimate genetic goals will dictate which you use. FTDNA tests not only autosomal, but also Y chromosome and mitochondrial DNA. They store your sample, so you can buy and upgrade tests at any time. So if you plan to start small and go big later, this is the place to be. 23andMe offers limited health information and some estimates on Y chromosome and mitochondrial DNA, but they don’t actually test the Y or mitochondria in the autosomal test. The science behind their estimates is sketchy at best…. but to be honest, the science behind genetic health information is sketchy too. If that’s your bag, get on with your bad self, but personally I see no point in paying 23andMe just for that information as there are sites that do it for free (or $5) from one of the other two site’s data. Finally, is straight autosomal. No Y. No mitochondria. All three will give you ethnicity estimates and they may vary on that as the science is, again, new and a bit sketchy. But all three will cousin match you, which is what genetic genealogy concerns itself with. In that regard, consider size of database and responsiveness. has become the place where people test if they want to actually connect the dots on their tree and confirm family information. Responsiveness of other testers to inquiries is varied on all three tests and I would recommend you give people time to respond and accept it if it never happens. Overall, I’ve found other testers to be helpful and excited to share data.


What’s Important
There are a number of tools to help in organizing your genetic research, but whether you’ll use them or not really depends on how tech savvy you are. At the core, however, let me tell you that you need to just start at the top of the list. Each site will give you a list of testers that match you and that list will usually be sorted by closest estimated relationship to furthest. Start with the closest. Whether you make paper notes, add them to a tree in progress as you confirm their connection to your real tree, or create digital archives of data won’t matter. Start at the top, and here’s why: by confirming the closest relative first, you’ll find links to the further relatives. You’ll also not get overwhelmed and lost. Lists can be several hundred pages long once the databases have been thoroughly compared (244 4th cousins myself!). You may use tools that bot crawl your lists and sort them for you, but if you’re diving in for the first time, I can’t emphasize enough just starting at the top. Each site has the ability for matches to connect a family tree to their tests, and in this regard does the best job. If they don’t have a tree available, message them and move on to the next one. You won’t be able to connect everyone immediately, but just like any puzzle, you work the pieces you know and it will build the picture for the ones you don’t.


Next Steps
No matter your organization or your tools or where you tested, the most important part of genetic genealogy will always be genealogy. The better the research, the better the matching. You’ll have good luck if you have adequately researched every line of your ancestors back to your 7th great grandparents… but how many of us have every line back that far? Surely we lose someone somewhere (especially women with no maiden names). More than just the ancestors, how far down you’ve brought each line into the living descendants will help when your matches haven’t gotten very far in their own research. But no matter how far in one direction or another you go, accuracy will be key. You’ll need records to confirm you lines and give you names of descendants or ancestors to follow to find the ancestor that you have in common with your genetic cousin. Inevitably, you will find a genetic cousin who doesn’t seem to fit. Maybe it’s because of a name change that broke the line. Maybe a paternity issue. Maybe an unknown adoption. Don’t let it be because you picked the wrong records and followed the wrong ancestor in your research. Don’t let a glorious royal lineage blind you to the fact that yours was the cook and not the king. Check and then double check your research. DNA is not labeled. When you take these tests, it’s up to you to connect the cousin to the ancestor. Some will be easy. Some will seem to take forever as you eliminate possible lines when matches don’t match a known cousin who tested. But every genetic cousin is your blood, in one way or another. Another piece in your puzzle, another line in your story. Once you’ve tested, don’t give up on the real research.


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