Last Updated on October 14, 2025 by Kenneth Rodriguez
So Your DNA Results Are In. Now What?
You’ve spit in the tube, waited impatiently for weeks, and finally gotten that email. Your DNA results are ready. You log in, full of anticipation, and are immediately faced with a list of thousands of names. Cousins you never knew existed. It’s equal parts thrilling and completely overwhelming.
I remember my first time. I stared at my top match, a predicted second cousin named “Sarah,” and my mind raced. Who was she? How were we connected? I had no Sarahs in my family tree. I felt like I’d been given a thousandpiece jigsaw puzzle with no picture on the box and half the pieces missing.
Trust me, you’re not alone in that feeling. The initial excitement quickly gives way to a simple, daunting question: What do I do with all this? Interpreting DNA matches isn’t about magic. It’s a skill. And like any skill, it requires the right techniques. Let’s break it down, step by step.
First, Let’s Talk About What Those Numbers Actually Mean
Before you can solve the puzzle, you need to understand the pieces. Every DNA testing company gives you two key pieces of information for each match: the amount of shared DNA (measured in centimorgans or cM) and the predicted relationship.
Here’s the kicker: that predicted relationship is just that—a prediction. It’s an educated guess based on the amount of DNA you share. A second cousin and a first cousin twice removed could share the same amount of DNA. The label is a starting point, not a final answer.
The real gold is in the centimorgans. This number is a measure of your actual genetic overlap. More cM generally means a closer relationship. Think of it this way:
- High cM (e.g., 3000 cM): This is a close relative. We’re talking parents, siblings, aunts, uncles, grandparents, or halfsiblings. The connection is usually easy to spot.
- Medium cM (e.g., 75 400 cM): This is the sweet spot for genealogical breakthroughs. These are your 2nd and 3rd cousins. Close enough to find the connection, but distant enough that they might know family branches you’ve never heard of.
- Low cM (e.g., under 20 cM): These are your distant cousins. They can be useful for confirming deep ancestral lines, but they’re often the most challenging to place precisely.
The biggest mistake I see people make is taking the predicted relationship at face value. Don’t do it. Use it as a clue, not a conclusion.
The Single Most Powerful Technique: The Shared Match Tool
If I could only give you one piece of advice, this would be it. The shared match feature (sometimes called “In Common With” or “Shared DNA Relatives”) is your absolute best friend. It’s the secret weapon that turns a confusing list of individuals into organized family groups.
Here’s how it works. When you click on a DNA match, you’ll see an option to view your shared matches. These are people who share DNA with both you and the person you’re looking at. This simple action instantly groups people by their common ancestral line.
Let me give you a reallife example from my own research. I had a strong match, “John,” who shared 250 cM with me. I had no idea who he was. But when I looked at our shared matches, I saw a cluster of people with surnames from my maternal grandmother’s line. Bingo. John wasn’t a random mystery cousin; he was connected through my grandmother. That shared match list narrowed my search from my entire family tree to one single branch. It was a gamechanger.
Use this tool to sort your matches into sides of the family. If you’ve tested a parent, you can even label matches as “Mother’s Side” or “Father’s Side.” If not, look for shared matches with known cousins from one branch. This act of grouping is 90% of the battle.
Building Your Case: The Genealogical Proof Standard
DNA evidence is incredible, but it’s not standalone proof. You need to combine it with traditional paper trail research. This is where the real detective work begins.
The Genealogical Proof Standard is a framework used by professional genealogists, and it’s what you should aim for. It means you need to build a reasonably exhaustive case that leaves no other logical conclusion.
So, you’ve grouped a cluster of matches using the shared match tool. Now what?
- Build or Refine Their Trees: Look at the family trees of your closest matches in that group. No tree? Send a polite message. I often say something like, “Hi! I see we’re a close DNA match. I’m trying to figure out our connection. Would you be willing to share a little about your ancestry?”
- Look for the Intersection: Your goal is to find the common ancestor or ancestral couple that you and all these matches descend from. You’re looking for the same names, the same locations, showing up in multiple trees.
- Document Everything: As you find potential connections, document the DNA evidence AND the documentary evidence (census records, birth certificates, etc.) sidebyside.
Funny story: I once spent months trying to place a match named “Eleanor.” Our shared matches pointed to my greatgrandfather’s line. I scoured every record I could find for an Eleanor. Nothing. It wasn’t until I looked at her tree more carefully that I realized “Eleanor” was the name she used for her public tree, but her real name, found in her obituary, was “Nellie.” And there she was, my greatgrandfather’s niece, plain as day. The lesson? People aren’t always who they appear in their online profiles.
When the DNA Throws You a Curveball
Not every DNA story is straightforward. Sometimes, the results reveal family secrets. A predicted halfsibling where there should be a first cousin. A complete absence of matches from an entire grandparent’s line.
This is called an NPE, or NonPaternal Event—a genteel term for a break in the expected family line. It could be an adoption, a name change, or an undisclosed parentage event.
It’s emotionally tough. I’ve worked with people who discovered their father wasn’t their biological father through a DNA test. The initial shock is real. But here’s a pro tip from my own experience: handle these situations with immense care and empathy. The people on the other side of that match are real people with their own family stories and potential secrets. Before you send a message that could upend someone’s world, pause. Think. Be kind.
If you suspect an NPE, the Leeds Method is a fantastic visual way to sort your matches by grandparent. It uses a simple colorcoded spreadsheet to cluster your 2nd and 3rd cousin matches, making it visually obvious if a match doesn’t fit where they should. It’s a powerful technique for visualizing unexpected connections.
What’s a centimorgan (cM) and why is it so important?
A centimorgan is a unit for measuring genetic linkage. For you, the genealogist, it’s simply the number that tells you how much DNA you share with a match. It’s the most reliable data point you have, more so than the predicted relationship, because it’s a raw, objective measurement.
Why do I share different amounts of DNA with my known cousins?
Because of random recombination! You inherit 50% of your DNA from each parent, but it’s a random mix. You and your full sibling both got 50% from Mom, but it wasn’t the same 50%. So, you might share 65% of your DNA with one sibling and 55% with another. The same principle applies to cousins. You might share 400 cM with one second cousin and only 280 cM with another.
I have a high cM match with no tree. What’s my first move?
Your first move is the shared match tool. Even without their tree, you can see who else you both match. This will immediately tell you which side of your family they’re related through. Then, look at the trees of those shared matches to identify the common ancestral line. After that, a friendly, nondemanding message is your best bet.
Is it worth testing on more than one DNA site?
Absolutely. Different sites have different databases of testers. By testing on AncestryDNA (which has the largest database) and then uploading your raw data to a site like FamilyTreeDNA or MyHeritage, you dramatically increase your pool of potential matches. It’s like casting a wider net.
Your DNA Journey is Just Beginning
Interpreting DNA matches is a puzzle, a history lesson, and a detective story all rolled into one. It requires patience, organization, and a healthy dose of curiosity. You’ll have moments of frustration, sure. But you’ll also have those incredible “Aha!” moments where a name from a century ago suddenly becomes a real person, connected to you by a specific, measurable thread of DNA.
Don’t try to solve everything at once. Pick one cluster of matches. Focus on one brick wall. Use the shared match tool, build your case with documents, and talk to your cousins. Your family story is waiting in those thousands of names. Go find it.