What’s a “good DNA match,” in genetic genealogy terms? Here’s what to look for in your DNA matches.
When looking at your DNA test results for genealogy, you may have heard that you should focus on the “good matches.” But what exactly does that mean? Both of those words are very ordinary, and yet it can be very difficult to decide which individuals on your long list of autosomal DNA matches is in fact a good match.
A good DNA match
Remember that the autosomal DNA test is the one that provides you genetic cousins from both your mom’s side and your dad’s side. But these genetic cousins come in the form of a long list of names, with no immediate indication of their relationship to you. Are they all good matches?
Well, yes, and no. Yes, the fact that these individuals are showing up on your match list means that you likely to share common ancestry. However, when we get past the fourth cousin mark, and possibly the fifth cousin mark, the chances that you share multiple distant common ancestors instead of a single recent common ancestor are very likely.
What I mean is, the farther back your connection, the more difficult it will be to identify—and then be certain—that a single common ancestor is the source of your shared DNA.
So I wouldn’t consider those distant cousins to be good matches right away, as a good match is someone with whom it is likely that you can identify your common ancestor.
Your closer genetic cousins
So that still leaves most of us with a fair amount of second, third, and fourth cousins. (Some people even have closer matches they don’t recognize.) Are all of those good matches? By the above definition, those seconds and thirds are good matches as it is likely you can find your shared common ancestor.
Before deciding about those fourths, you need to take a good look at your own pedigree chart. If you come from ancestors who were rather prolific in their child-bearing and rather adept at keeping those said children alive into their own reproductive years, you may have the same problem with your fourth cousins as you do with your fifth and sixth cousins. That is, for some fancy genetic and statistical reasons, many of those showing as fourth cousins may actually be fifth or sixth cousins a few times over.
So, how can you identify your best matches from among the throngs of those fourth cousins clamoring for your attention?
Genealogy. That’s right—the stuff you already know how to do.
Combining genealogy and genetics
Your best matches are the ones who not only share your genetics, but share common genealogical elements with you as well. So the best route to finding your best matches among the fourth cousins at your autosomal DNA testing company is to search your match list for surnames and locations found in your own pedigree chart. Those sharing your genetics AND one or more of your common genealogical elements are those that are most likely to lead to a genealogical discovery, and are therefore your best matches.
You don’t have to do this all on your own, though! We are here to help you every step of the way. That’s why we’ve put together our free guide, Finding an Ancestor Using DNA, to get you started. Download a copy of your own so you can start using your best matches to find those missing ancestors.