Your Ancestry DNA Results Are In: First Steps in Genetic Genealogy

The email arrives, you open the app, and there's a colorful map with percentages next to a long list of strangers who share your DNA. Most people spend an evening on the map. For family history, the strangers are the more useful part. This guide covers what to do in your first few weeks so the list starts to make sense.

Two different results: ethnicity and matches

Your results page holds two separate things, built in different ways.

The ethnicity estimate compares pieces of your DNA with reference groups, sets of people whose families lived in one region for many generations. Ancestry says its panel now has more than 300 such groups. It adds up which region each piece of your DNA most resembles, then reports percentages with a range for each one. Ancestry keeps updating its reference groups, so your percentages can change over time. Our explainer on how ancestry percentages actually work goes deeper, and why siblings get different results shows why two children of the same parents rarely match exactly.

DNA matches are other people in the same database who share stretches of DNA with you. Each one is a real person with a real connection to your family, somewhere back in time. That's where genealogy happens.

What centimorgans mean

Next to each match you'll see a number followed by "cM". A centimorgan is a unit geneticists use for how often DNA gets shuffled, or recombined, as it passes from parent to child. The US National Human Genome Research Institute notes that one centimorgan corresponds, on average, to roughly a million base pairs of DNA. Ancestry's help center puts it simply: centimorgans measure probability, not physical distance.

For genealogy, the practical points are these:

• More shared cM usually means a closer relationship.
• The same number can fit several relationships. A half-sibling, a grandparent and an aunt can share similar amounts. So can several kinds of cousin.
• The predicted relationship is a best guess. Read it as "probably in this range", not as a label.

When you want to see which relationships fit a number, use the Shared cM Project tool. The project was created by genetic genealogist Blaine Bettinger and collects shared-cM figures that testers submitted for known relationships. The interactive version at DNA Painter lets you type in a cM value and see which relationships are possible and how likely each one is. We haven't copied ranges here because the tool is the better reference.

Sort your matches by family side

Your first real job is to work out which side of the family each match belongs to. Known relatives make this much easier.

• Use shared matches. Ancestry shows, for any match, the other people on your list who also match them. If your known maternal first cousin shares a match with you, that match is probably on your mother's side.
• Use groups. Ancestry lets you create custom color-coded groups (up to 24 with a DNA kit, or 64 with a family history membership). Make one for each side or line as you learn it. A match can sit in more than one group.
• Filter. You can filter by unviewed matches, starred matches, matches you've added notes to, matches with linked trees, and matches whose trees show common ancestors with yours.

If a parent is willing to test, their results sort your list quickly: anyone who matches you and your mother is likely on her side. Ask kindly, and accept a no.

The Leeds Method in plain steps

Genealogist Dana Leeds developed a simple way to sort matches into groups that often line up with your four grandparents. It uses nothing more than shared matches and a spreadsheet or a set of colored groups.

1. Pick the right matches. For people looking for an unknown parent or grandparent, Leeds recommends using matches who share between 90 and 400 cM with you, which mostly catches second and third cousins. If you know your family, she suggests using matches who share one of your grandparents and leaving out anyone who shares two, such as full first cousins. Including them can collapse four clusters into two.
2. Start at the top. Take your closest qualifying match and give them a color.
3. Color their shared matches. Open that match's shared matches and give the same color to everyone who appears in your working list.
4. Move to the next uncolored match. Give them a new color and repeat. Keep going down the list.
5. Allow overlaps. Some matches will land in two clusters. Leeds gives that match both colors, but doesn't give both colors to their matches.
6. Name the clusters. Use known relatives, trees and surnames to work out which grandparent each color points to.

Expect some mess. Leeds notes that half relationships can split one grandparent into two clusters, that pedigree collapse (cousins marrying cousins somewhere back in the tree) can make matching harder, and that ending up with three clusters or seven is fine. What matters is working out what each cluster means. She also says the method won't directly give you great-grandparent clusters. For that, look at shared matches within one grandparent's cluster. She keeps a separate spreadsheet for each testing company rather than mixing them.

Build a tree your matches can meet

DNA tells you who you're related to. A tree tells you how. You need both.

• Start with what you know. Add yourself, your parents and your grandparents, with dates and places. Ask older relatives and collect documents while you can.
• Link the tree to your DNA. Ancestry's ThruLines feature suggests how you might be related to matches through common ancestors in linked trees. It needs a tree linked to your DNA that's public or private-but-searchable, works best with at least four generations, and requires an Ancestry membership.
• Treat suggestions as hypotheses. Ancestry itself says ThruLines suggests possible relationships but doesn't prove them, and that accuracy depends on the trees it draws from. Check each link against records and against the shared cM.
• Use your matches' trees. When a match has a tree, look for surnames and places that overlap with yours. When they don't, a quick sketch of their family from public records can still reveal the link.

Think about privacy as you go. A public tree with full details of living relatives is visible to strangers. You can keep living people minimal and still get the research benefits.

Contacting matches politely

Many matches never reply. Some check their accounts rarely, and some tested only for the ethnicity map. A short, friendly message gives you the best chance.

• Say who you are and how much DNA you share.
• Say what you're researching, with one or two surnames or places.
• Ask one specific, easy question.
• Offer something back, such as a look at your tree.
• Don't lead with a theory about who their parent or grandparent "really" is.

Matches sometimes uncover hard news: an unknown half-sibling, a different biological parent, a donor-conceived relative. Go gently, give people time, and respect a request to stop. If you're the one facing a surprise, Right to Know offers support for people affected by misattributed parentage, adoption and donor conception. Our guide on how one relative's test affects the family covers the wider picture.

Keep notes as you go

A month in, you'll have dozens of half-remembered clues. Write them down from day one.

• Use the notes field on each match. Record the side, the cluster, and any guess about the common ancestor.
• Keep a simple spreadsheet. Useful columns: match name, shared cM, testing site, side, cluster color, possible common ancestor, evidence, date contacted, reply.
• Separate guesses from proof. Mark each conclusion as a hypothesis until records and DNA agree.
• Log your sources. Note where every date and name came from so you can recheck it later.

Where to go next

Once your list is sorted, you can widen the net. Some sites let you upload your raw data to find matches who tested elsewhere. Read the privacy settings to check before uploading first. If you're curious about a direct paternal or maternal line, haplogroups explain what Y-DNA and mitochondrial tests add.

Common questions

Medical disclaimer. GenomeTesting.org publishes educational content about genetics and consumer genomic testing. Nothing here is medical advice, a diagnosis, or a substitute for care from a qualified clinician or genetic counsellor. Decisions about testing, treatment, or interpreting your own results should be made with a healthcare professional who can see your full history.

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