Why Your DNA Test Matching Results Make No Sense Without a Family Tree

Andy Lee
2 hours ago
4 min read

So... you tested with MyHeritage DNA—or maybe you transferred your results to One of the biggest mistakes I see—over and over again—is folks expecting their DNA test to do all the work. They crack open their results, see an unexpected ethnicity, or notice a missing percentage they were sure they’d inherited, and then? Panic. Full-blown “the test is broken” or “my entire life is a lie” levels of panic.

Let’s clear something up: DNA tests are powerful tools, but they are not crystal balls. And they definitely don’t come with the answers neatly spelled out.

Close-up of a blue DNA double helix against a gradient white to pink background, highlighting the molecular structure's complexity and elegance.

DNA Alone Won’t Tell You Everything

Your DNA test didn’t get it wrong—it just didn’t tell you what you thought it would. Most of the time, it’s not the test that’s the problem. It’s the interpretation. DNA results are based on reference populations (which aren’t always as robust or inclusive as we’d like), and unless you know your own family history, you’re going to have a hard time reading the map.

If you don’t know where your ancestors lived, who they married, or how your family migrated over time, how can you expect to recognize the story your DNA is trying to tell?

Spoiler alert: You shouldn’t be dropping $79 on a DNA test just to get a splashy ethnicity pie chart. That’s like buying a treadmill to hang your laundry on. Instead, test to better understand your family story. Use it as a starting point—not the whole journey.

And no, a DNA test isn’t going to build your family tree for you. It’s not a magic tree planter. It’s more like a puzzle where half the pieces are blank until you dig into the records.

If your eyes just flicked to a 12 cM match and thought, “But she has Grandma’s eyes!”—slow your roll. Segments under 15 cM are way more likely to be false positives. That’s not a cousin. That’s a coincidence.

What Happens When You Only Use One Tool?

Here’s where things go sideways: You rely only on DNA and expect it to tell you who your great-grandparents were. Or you rely only on paper records and assume every detail is 100% accurate.

Newsflash: People lied. Babies were adopted. Names changed—sometimes on purpose. If you’re not verifying your paper trail with DNA, you could be climbing the wrong family tree altogether. If you’re not supporting your DNA matches with real records, you’re just guessing. And guessing isn’t research.

DNA Matches Don't Lie—But They Don't Spill the Whole Truth

Let’s say you share 865 cM with a stranger. That’s a good-sized match—enough to suggest they’re a great-aunt, a half-uncle, or a first cousin once removed. But that’s just a range. DNA might tell you which side of the family they’re on, and sometimes whether the connection is maternal or paternal, but it won’t name names.

That’s where traditional genealogy steps in and connects the dots. Here’s how paper records back up your DNA detective work:

Vital Records (birth, marriage, death): Anchor people in time and place.
Census & Land Records: Show who lived with whom and when.
City Directories: Andy and I used these to solve the mystery of my Grannie’s biological father. Long story short: Three brothers were candidates. Only one lived near her and worked at the same railroad. Hello, Delbert Hankinson.
Newspapers: Sure, they weren’t designed for DNA work, but they’re gold for filling in the details that let you match a name to a segment of shared DNA.

NA Can Point the Way, But Genealogy Names the Names

Adoptees and folks with unknown parentage often feel stuck. DNA tools like the Leeds Method and WATO (What Are the Odds?) can give you a strong hypothesis about which family your missing parent came from. But again—no test is going to hand you a birth certificate.

You’ll need to dig through:

Census records and city directories to place your candidate in the right place and time.
Marriage and divorce filings to understand family structure.
Obituaries, probate files, even military pensions—anything that reveals relationships DNA can’t confirm.

When DNA Drops a Bombshell, Records Bring the Truth

Found out your dad isn’t your dad? Join the club—NPEs (non-paternal events) happen more often than people think. DNA might point to the right family, but if there were multiple brothers (or cousins) in the picture, good luck figuring out which one was your biological grandfather without digging into the records.

Want to know who was living where, when, and with whom? That’s what paper trails are for.

DNA Ethnicity Estimates Are Just That—Estimates

If you’re shocked that your 23andMe results say you’re 10% Scandinavian but your tree doesn’t show a single Norseman, take a breath. Ethnicity estimates are just educated guesses based on reference populations. And those can vary wildly between companies—or even between updates.

What doesn’t change? Historical documents. If you can trace an ancestor who immigrated from Norway in 1884, that’s confirmation. No algorithm needed.

Green DNA strand on left, text on green background: "Make more sense of your genetic genealogy research with these free guides. GET STARTED."

Bottom Line: DNA Gives You Clues. Records Give You Answers.

You don’t have to choose between DNA testing and paper trail research. You need both. One without the other is like trying to solve a mystery novel after skipping every other chapter.

Want to see how this works in real life? Our YouTube channel is packed with tutorials showing exactly how to turn DNA matches into family trees. Whether you’re dealing with adoption, NPEs, or just trying to make sense of that 865 cM cousin who showed up last week—we’ve got you covered.

Got a question? Drop it in the comments. I’ll help you find your next step.

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