DNA Testing Limitations

When it comes to setting DNA testing goals for family history, you have to know your limitations. You want realistic expectations! Increasingly, the list of what DNA testing CAN’T do is getting shorter. But there is still a list. Here it is.


DNA testing limitations What DNA Cant Do Limits of DNA Testing for Family History DNA Testing Goals IO (1).png

What DNA Alone Can’t Do

Can-do people rarely like to talk about what just. isn’t. possible. But the truth is, if you don’t know your limitations, you might set unattainable goals which lead to disillusionment and frustration down the road.

Good news: the list of what DNA can’t do for your family history is getting shorter. More people around the world are testing. DNA tools and analysis are improving. But there are still limits. Here are four things that DNA all by itself simply cannot do for you.

1. DNA can never provide the name of an ancestor.

DNA alone is not going to deliver your ancestors’ names to you on a genetic silver platter. (Tree reconstruction tools such as 23andMe’s Family Tree, MyHeritage’s Theory of Family Relativity and AncestryDNA’s ThruLines are pushing this direction, but none are foolproof and the latter two require family tree data—and of course you have to have DNA matches who point you in the right direction.)

Now, if your close relative tests at the same company you do—and the screen name they use is their real name—then yes, you’ll get their real name delivered on a silver platter right to your match list. But what I’m talking about is the identity of your ancestors: grandparents, great-grandparents, etc.

Your DNA Guide the Book and Finding an Ancestor Quick Reference Guide.png

What DNA CAN do: your DNA test results can eventually lead you to the identify of unknown ancestors, but you also need a healthy stack of real genealogy records, family tree data, fruitful DNA matches and good analysis. My quick reference guide, Finding an Ancestor Using Your DNA, introduces this methodology, which I cover even more extensively in Your DNA Guide—the Book.

Get inspired with this success story: Who’s Your Granddaddy?

2. DNA can never provide a definitive relationship.

Even with the amount of DNA shared by biological parents and full siblings, there is always more than one possibility as to how you’re related to someone. The more distantly you’re related, the more possibilities for how you’re related. The genetic distance between even these half-sisters, below, allows for several possibilities for how they might be related:

DNA testing limitations half siblings relationship possibilities.jpg

How am I Related to My DNA Matches Shared Centimorgans cM 11.png

What DNA CAN do: As shown above, DNA gives us a genetic relationship range, or list of possible relationships. We have to use other resources—historical records, trees, DNA analysis—to help us figure out which of the possible relationships is accurate (or at least most likely). I walk you through this process in Your DNA Guide—the Book. You can also start learning with this article on how to determine relationships to DNA matches.

3. Autosomal DNA cannot currently reach back farther than five or six generations.

Autosomal DNA testing is most common kind of DNA testing. That’s what is sold by AncestryDNA, 23andMe, MyHeritage, Living DNA and Family Tree DNA (the Family Finder test). It’s great because it reveals your heritage on both sides of your family tree. Five or six generations sounds like a lot, but many people want to go deeper than their 3x or 4x great-grandparents.

What DNA CAN do: Those five or six generations have potentially produced hundreds or even thousands of living relatives. DNA can help connect you to them and can reveal clues about how you’re related to them. (In the process, you may come across a lot of removed cousins.)

DNA Story Connection Identity Kindred Spirits Kin 11 (1).png

Connecting with your DNA matches can help you rebuild your family tree—along with your sense of family identity and connection. Get inspired with this story about second cousins who connected meaningfully: DNA Connects Kin—and Kindred Spirits.

4. YDNA and mtDNA have strict inheritance patterns that limits their use.

YDNA testing is only available for men, and looks only at paternal lineage: a man’s father and his father and his father, etc. mtDNA testing (which both sons and daughters inherit) looks exclusively at the lineage of your mother, her mother, and her mother, etc. A lot of relatives who don’t fall on those lineages—such as your mother’s father’s mother’s people—are untouched by your YDNA and mtDNA tests.

What DNA CAN do: DNA does reveal unique clues about your maternal and paternal lines, and can connect you with relatives on these lines (though often, much more distant relatives). You can learn about deeper ancestry and migration patterns through their haplogroup assignments. You can also use YDNA and mtDNA in targeted ways to ask specific questions about these branches of your family tree.

Get inspired: read about how mtDNA clues helped me identify relatives on my adopted mother’s biological family tree.

DNA testing limitations: Not so limiting, after all

In setting out to clarify what DNA cannot do alone, it looks like I couldn’t help but reveal what it CAN do when you bring your best game to it. Read our growing DNA Stories series. You’ll see for yourself that DNA alone didn’t answer their burning questions about their roots—but it played a critical role.


Source: Your DNA Guide Blog – Your DNA Guide https://www.yourdnaguide.com/ydgblog/

Posted On: January 5, 2021 at 03:51PM