Giving Thanks (DNA Painter)

In the United States, we celebrate a day of thanks every November. So, this month’s post deals with something I am thankful for in the genetic genealogy community. There are SO MANY people here who deserve our gratitude: citizen scientists, search angels who help adoptees, folks who answer newbies’ questions on social media, kin who graciously agree to take a DNA test… it was hard to pick one.

In the end, I decided to write my thanks to someone who has recently developed and shared an amazing (and free!) new DNA tool: Jonny Perl and his DNA Painter.



The website  is VERY user friendly and has everything you need to know to get started. Be sure to check out the Help and Advice section on the home page. It will direct you to an excellent 45-minute YouTube video by Blaine Bettinger, as well as social media sites where you can ask questions and keep posted on all the ongoing enhancements.

What exactly is DNA Painter? It’s a tool for those of us who have our autosomal DNA results at a site with a chromosome browser. In other words, you need to know the chromosome where you match someone and the start and end locations on that chromosome for each segment you share with a ‘cousin’. (AncestryDNA doesn’t offer this, but the FamilyFinder test at FamilyTreeDNA and the 23andMe test do. AncestryDNA users can copy their raw DNA data to GEDmatch for free to get chromosome matching segment information with ‘cousins’ who have also copied their data to GEDmatch.)

The goal is to identify which parts of which chromosomes came to you from which grandparent—or even further back. We know we have one copy of each autosomal chromosome from Dad and one from Mom, so entering data from parents, siblings, aunts, uncles, or first cousins doesn’t help us narrow it down beyond paternal or maternal sides. (They are hugely valuable to have; just not what we want to enter in this tool.) We want to map our matches with our parents’ first cousins, our own second cousins, or relatives more remote. 

The DNA Painter homepage, Help and Advice section, and How to Use section will walk you through the steps. Image 1 shows graphically in DNA Painter the segments where my sister S matches our mom’s paternal first cousin. (All screen captures here show fewer than 23 chromosomes, to improve legibility.)

Image 1.


The top row of each chromosome is the paternal copy; the bottom is the maternal copy. The red segments show where S got DNA not just from Mom, but specifically from Mom’s dad, since it matches Mom’s paternal 1st cousin there. If a new DNA cousin matches S on any of these red segments, and if we can confirm it’s on S’s maternal side, we’ll know that it’s specifically from Grandpa’s line.

Image 2 is the same chromosome map, updated to include S’s matches to our dad’s paternal first cousin, shown in green. Notice the “key” to the right: we can identify segments who share the same source with a label, such as Hammond-Griffith or Harrigan-Flynn.

Image 2.

Sis S DD

We can add match data from more distant cousins too. The tool allows us record the segment location, the person we match, who our common ancestor is, any notes that we want. (More on that below.)

Image 3 shows the current work-in-progress status of my own chromosome map.

Image 3.

Ann Nov 2017

Unlike my sister’s profile, where I labeled the groups by Most Recent Common Ancestral couple (e.g. Hammond-Griffith), I’ve chosen to use MDIDS in my own map. MDIDS is Most Distant Identified DNA Source (e.g. 006-Harry Hammond 1895-1966). Harry, ahnentafel number 006, was the son of Hammond-Griffith. For more details about MDIDS, see my blog post here. I’ve expanded my key in image 4. You can see I also sort it by grandparent, and within grandparent, by ahnentafel number.  I also color code my groups by grandparent line. Dad’s father and his ancestors are green colors; Dad’s mom’s line is yellow. Mom’s father’s line is shades of blue and her mother’s line is shades of red. DNA Painter lets you pick colors, or you can let the tool assign them randomly.

Image 4.

Ann key Nov 2017


You can label your group by MRCA couple or MDIDS or ahnentafel numbers or however you like. 

In DNA Painter, you can also hover over a segment to see the group name that segment belongs to, or click the segment for the other details you’ve provided for that segment. You can also expand an individual chromosome to visualize all the matches you’ve entered on that chromosome, and again, select a segment to read notes. This is one way to easily identify triangulations and theories you might want to capture. See image 5.

Image 5.

Ann chr11 Nov 2017

In this example, the pop-up box is obscuring the selected green segment, which occurs immediately below the dark and light green segments shown. I believe I got this DNA segment passed down from Barbara Conneely 1828-1923. The pop-up box gives the start and end points on chromosome 11 where I match “K” who tested at Family Finder. My notes say that this segment triangulates with Paul, who is also descended from a Conneely. K’s father was born in the same village in Ireland that Barb Conneely lived in 1855. (You can enter whatever notes you want: when you emailed the match, his/her GEDmatch kit number, whatever….)

The bottom section in Image 5, above, shows that I have many maternal matches on this chromosome 11 too, including several triangulation groups shown in blue. (The varying shades of blue do not reproduce well in the image, but I can select specific segments for more details.)

Clearly, I think DNA Painter is a fun and easy way to organize and manage our DNA match data.

Another valuable benefit to DNA Painter is how vividly it can pinpoint bad assumptions. Consider my green matches near the far end of chromosome 11. I’m very confident those are on my father’s father’s side—Granddad. Suppose I get a new, smaller match, maybe 8 cM, in that same area. The new cousin shares a surname and a possible Most Recent Common Ancestor on my father’s mother’s line—Nana. (That would get a shade of yellow in my map.) If I enter the new segment, look at chromosome 11, and see that I have both yellow and green in the same or overlapping section of my paternal chromosome 11, then I know that I’ve mapped something wrong. Given the strength of my green evidence, I suspect that the segment with my new cousin didn’t come to me from Nana after all.

That 8cM segment may be a false match: a genotyping error. Or the new cousin and I *may* share a common ancestor on Nana’s line, but we may have another common ancestor 8 or 10 generations back. That 8 cM segment could be from the other, as yet unknown, ancestor way back on Granddad’s line. Not from Nana at all. 

DNA Painter has lots of cool features, lots of benefits, and it’s constantly being enhanced. (For example, check out the Tools option from the toolbar along the top.) Register for a free account, explore the Help and Advice and How to Use, and dive in.

And thank you, * Jonny Perl *, for making our work with DNA so efficient and colorful and FUN!

Ann Raymont © November 2017

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