A DNA match list is a list of questions. Each entry — a name, a centimorgan value, a predicted relationship — represents a connection to someone who shares an ancestor with you, without telling you which ancestor, which line, or how far back. Segment analysis is the process of answering those questions by working with the underlying genetic data rather than the summary statistics, and DNA Painter is the tool that makes that analysis accessible to researchers who are not population geneticists.

Understanding how to use DNA Painter, what segment data actually means, and what conclusions you can and cannot draw from it is one of the most practical skills available to a serious genealogical DNA researcher. This article covers the workflow from start to finish.

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What DNA Painter Is

DNA Painter is an easy-to-use tool that helps genealogists make sense of DNA testing. By mapping segments of DNA to chromosomes, we can begin to see which ancestors gave us which pieces of DNA, and thus how new matches are related. As a result, DNA Painter has quickly become an essential tool for genealogists.

The site was created by Jonny Perl, a web designer and genealogy enthusiast based in London, who began with a spreadsheet to track his own segment data and eventually built it into the most widely used chromosome mapping platform available to consumers. DNA Painter is free to use for individual users, with a chromosome map, shared cM tool, and basic tree upload included. A premium subscription ($30 every six months or $55 per year) unlocks multiple DNA sample comparisons and a full family tree upload.

DNA Painter is not a testing company and does not store your raw DNA. It stores only the segment data you enter — start and end positions, chromosome numbers, and the centimorgan values from your DNA matches — along with the family tree information you associate with those segments.

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Getting Segment Data

Before you can use DNA Painter, you need segment data — the specific genomic locations where you and a DNA match share DNA. This data is expressed as chromosome number, start position, end position, and centimorgans. You can get matching segments from FamilyTreeDNA, MyHeritage, Living DNA, and GEDmatch. As of 2026, 23andMe segment data requires a paid 23andMe+ subscription.

FamilyTreeDNA provides segment data through its chromosome browser. Click “Detailed Segment Data” above the chromosome display to see a table of start positions, end positions, and centimorgan values, which can be copied directly into DNA Painter’s paint form.

MyHeritage provides segment data through its chromosome browser, accessible for matches above a certain threshold.

GEDmatch provides the most flexible segment comparison tools, including one-to-one comparisons with full position data that is essential for techniques like visual phasing (covered in the previous article in this series).

AncestryDNA does not provide segment data to users. Ancestry testers who want to build chromosome maps need to transfer their raw DNA to FamilyTreeDNA or GEDmatch, where segment data is available.

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Understanding What the Numbers Mean

Before mapping anything, it helps to understand what segment data actually represents.

Chromosome number (1–22 for autosomal DNA) identifies which chromosome the shared segment falls on. You have two copies of each chromosome — one from your mother, one from your father — and the segment could be on either copy. Without additional analysis, you don’t know which.

Start and end positions are measured in base pairs (the individual nucleotide letters that make up your DNA). A start position of 15,234,567 and an end position of 28,445,234 on chromosome 7 means your shared segment spans roughly 13 million base pairs in that region of that chromosome.

Centimorgans (cM) measure genetic distance — not physical distance in base pairs, but the statistical probability of recombination in that region. A segment of 20 cM is genealogically meaningful; a segment of 3 cM is probably too small to interpret reliably and may be identical by chance rather than descent. Most serious analysts set a minimum threshold of 7–10 cM before treating a segment as genealogically significant.

SNPs (Single Nucleotide Polymorphisms) are the individual marker positions that testing chips measure. A segment with 2,000 SNPs is generally more reliable than one with 500 SNPs at the same centimorgan value.

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Building a Chromosome Map in DNA Painter

The basic workflow in DNA Painter is straightforward: you enter segment data from a known relative, assign that data to a specific ancestor or ancestral couple in your family tree, and watch your chromosome map fill in with color-coded segments attributed to different ancestors.

Start with the closest relatives whose segment data you have access to — a first cousin, a known second cousin, a parent or grandparent if they’ve tested. Paint those matches first. A segment shared with a first cousin on your mother’s side covers one quarter of your family tree; a segment shared with a known first cousin on your maternal grandmother’s side narrows it further to one eighth.

As you paint more known relatives, the gaps in your chromosome map fill in. Segments you share with three or more relatives whose common ancestor with you is the same person become triangulated segments — the strongest form of segment evidence available in autosomal DNA analysis.

The site lets you paint your DNA by using the segments you share with your matches. When you create a blank chromosome map, this represents your chromosomes, with a maternal and paternal chromosome in each pair. You don’t need to paint yourself because the unpainted map already represents you.

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The Tools Within DNA Painter

The Shared cM Tool is one of the most widely used features on the site. Enter the number of centimorgans you share with a match, and the tool displays the range of possible relationships and their statistical probabilities based on data from the Shared cM Project — a collaborative database of centimorgan values from thousands of known relationships. This is the standard first step when encountering an unfamiliar match: enter the cM value and see which relationships are plausible.

What Are the Odds? (WATO and WATO Plus) is a specialized tool for investigating unknown parentage and other family mystery cases. You identify at least two matches whose common ancestor with each other is documented, and WATO calculates the probability that an unknown target person occupies various positions in the documented family tree. WATO Plus, released in 2024, extends the original tool with additional features for complex cases.

The Cluster Mapper imports autocluster results from Genetic Affairs, DNAGedcom, GEDmatch, or MyHeritage and maps them directly into a DNA Painter chromosome map. This bridges the clustering techniques discussed earlier in this series with the segment mapping work covered here, allowing researchers to see both their match clusters and the underlying chromosomal segments in a single integrated view.

AncestryDNA’s Chromosome Painter (beta) is a separate tool Ancestry introduced that maps ethnicity estimates onto individual chromosomes. Jonny Perl has created a way to import the Ancestry ethnicity painting into DNA Painter tools. While ethnicity-based chromosome painting has the same limitations as ethnicity estimates generally (discussed in an earlier article in this series), it provides a visual starting point for understanding which chromosomal regions carry which population signal.

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What Segment Overlaps Do and Don’t Mean

One of the most common misunderstandings in chromosome mapping is what it means when two matches share segments in the same region of the same chromosome.

When you see segments overlapping on a chromosome, this doesn’t necessarily mean that these people share the same segment of DNA. You have two copies of each chromosome — maternal and paternal — and both are represented in your chromosome map. If Match A’s segment is on your maternal chromosome and Match B’s segment appears to overlap it visually, they may not share that segment with each other at all; Match B’s segment might be on your paternal chromosome at the same chromosomal location.

True triangulation — which involves confirming that all three parties (you, Match A, and Match B) actually share the same segment with each other — requires additional verification, typically by checking whether Match A and Match B appear in each other’s match lists and whether they share the same segment region. Chromosome mapping can help you understand how autosomal DNA inheritance works and can be useful when working with DNA matches, though research connecting segments to specific traits is still in its early stages.

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For Dillman Researchers

The most immediate application of DNA Painter for Dillman researchers is segment analysis of the Dillman DNA Project participants on FamilyTreeDNA. Project members who have taken the Family Finder autosomal test and share segment data with each other can map those segments and begin to identify which chromosomal regions are shared specifically among Dillman-surname descendants — and which shared regions are likely attributable to general German regional ancestry rather than a specific Dillman line.

For researchers who have a known Dillman relative who has tested — a cousin, aunt, uncle, or sibling whose Dillman ancestry is documented — painting that relative’s segments provides an anchor for the entire Dillman line. Every new match who shares segment data in those same regions becomes a candidate for connection through that Dillman ancestor. The chromosome map doesn’t solve the genealogical problem, but it constrains it — and a well-constrained problem is a solvable one.

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Sources

DNA Painter. “Frequently Asked Questions.” dnapainter.com. Accessed July 2026. dnapainter.com/help/faq.

DNA Painter. “How to Use DNA Painter to Map Your Chromosomes.” dnapainter.com. Accessed July 2026. dnapainter.com/help/how-to-use.

DNA Painter. “Match Data: Getting Segment Data from Testing Sites.” dnapainter.com. Accessed July 2026. dnapainter.com/help/matchdata.

The DNA Geek. “Chromosome Painting at Ancestry.” March 16, 2026. thednageek.com.

Who Do You Think You Are Magazine. “DNA Painter: What Is It and What Are Its Key Features?” November 28, 2023. whodoyouthinkyouaremagazine.com.

Genomelink. “5 Things You Should Know Before Using DNA Painter.” February 27, 2025. genomelink.io.

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Note: This post was researched and written with the assistance of artificial intelligence (AI). All content has been reviewed for accuracy as of September 2026. All errors are the responsibility of the author.