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Using DNAPainter

It used to be that “work” was the big four-letter word in The Legal Genealogist‘s vocabulary.

It was always getting in the way of doing the things I wanted to do… like genealogy.

These days, the more usual big four-letter word is “time.”

As in the common complaint: “I need more time for this.”

Or as in the even more common whine: “I don’t have time to figure this out!!”

And nowhere is this more of an issue than in working with our DNA matches — trying to identify the common ancestors and work with our known and newly-discovered cousins to find out more about our ancestors using autosomal DNA tests like the ones from Family Tree DNA, MyHeritageDNA, 23andMe, AncestryDNA and the like.

With literally hundreds of new matches appearing every week for those of us who’ve done widespread autosomal DNA testing, finding time to get the most out of those matches may be the hardest thing of all. And even finding the time to use the tools available today to work with those matches can be a challenge.

Enter DNA Painter, Grand Prize winner of this year’s RootsTech Innovation Contest, developed by British web and applications developer Jonny Perl. (For more about the developer, see Jill Ball’s interview “Jonny Perl at Rootstech.”)

It’s a tool that’s easy. That’s intuitive. And — best of all — that doesn’t take a whole lot of time before you can start seeing its power and usefulness.

Here’s what the tool’s website says about itself:

DNA Painter is a website that you can use to visualize and make notes on your DNA matches. The site is intended for genealogists and family history enthusiasts who have taken a DNA test. We have a natural desire to discover who our matches are and how we’re related to them, but interpreting test results can be a challenge, with unfamiliar names and pages of numbers.


DNA Painter helps by providing a platform where you can:


• Enter the numerical information provided by the testing company for each match and visualise it on your chromosomes
• Make notes and indicate how certain you are that you’ve identified correctly how you are connected to each person


… This process is known as chromosome mapping.1

Sounds great, doesn’t it? And I’ve known about DNA Painter for months — since it was first launched in beta in 2017. But I didn’t get around to playing with it until yesterday because of that four-letter-thing… time.

Boy, am I sorry it took me this long.

Because after just a few hours of playing with it yesterday, here’s a sample of what I was able to put together for one of my maternal uncles:

This is just the first 12 chromosomes for this particular uncle, showing how his DNA and that of known cousins lines up to tell us which of several sets of ancestral couples the DNA has to have come from.

On his paternal side, for example, the dark blue comes from the parents of his father (my grandfather) Clay Rex Cottrell. So it represents his grandparents, my great grandparents, Martin Gilbert “M.G.” and Martha “Mattie” (Johnson) Cottrell. The lighter blue is from M.G.’s parents, George and Martha Louisa (Baker) Cottrell.

On his maternal side, the red comes from the parents of his mother (my grandmother) Opal (Robertson) Cottrell. So it represents his grandparents, my great grandparents, Jasper and Eula (Baird) Robertson. The orange is from Jasper’s parents, Gustavus and Isabella (Gentry) Robertson, and the lighter gold from Isabella’s parents, Elijah and Wilmoth (Killen) Gentry.

And why is that useful? As the website explains: “The end goal of using DNA Painter is to be able to map your chromosomes to your ancestors. You can use known matches to help you identify unknown matches. As soon as you know which ancestor was the source of a specific segment, you will have a better chance of identifying any new DNA matches who share this segment. Imagine if all your DNA matches were mapping their chromosomes like this! Mysteries could be solved much more quickly and easily!”2

In other words, once I get as much information entered into the system as I can, when a new match appears, I can immediately compare the segments we share in common to the painted segments and I’m going to have a pretty good chance of knowing what line or lines of descent that new match and I have in common. I won’t be wasting my time floundering around trying to figure out which set of great grandparents or second great grandparents we might share.

In other other words… a time-saver.

Now… a couple of key of caveats. First and foremost, read the help pages for a better understanding of the tool than any blog post can provide, and watch the video introduction by Blaine Bettinger for some great advice on how to get the most out of the tool.

Yeah, that takes a little bit of time — maybe an hour total to read the help, watch the video and absorb the information. But — trust me on this one — it’ll save you some time once you get started with painting.

Second, understand that the tool requires that you have at least some known cousins among your matches — second or third cousins are the best — to be able to use it effectively. You have to start painting with the data of people where you know how you’re related before you can use the results to help with the data of people where you don’t know how you’re related.

So the more cousins you’ve already tested, the better off you’re going to be. Which means, of course, that you need to get more of those second and third cousins to test for you.

But the biggest limitation of all is that you have to be able to access segment data — the exact information about where you and your match share DNA — in order to use the tool for that match at all. For a great tutorial on how to get the segment data, see Roberta Estes’ blog post, “DNAPainter – Mining Vendor Matches to Paint Your Chromosomes.”3

That means you can’t use it directly for matches who’ve only tested at AncestryDNA — the one and only DNA company that won’t let us access segment data. To use it with our AncestryDNA matches, we’re going to have to ask them to upload their data to Family Tree DNA, through its Autosomal Transfer system, to MyHeritageDNA via its upload program, or to the free third-party website

And if you’re going to ask a match to upload to any of these, make sure you remind them to read the terms and conditions and privacy policy of each site, so they know exactly what uses can and can’t be made of their data. This is more and more important these days, particularly as the more public DNA databases like GedMatch are being mined for forensic purposes.4

By the way, the privacy policy at DNA Painter is straightforward, and provides, in part that:

• Your profiles cannot be viewed by any other user unless you explicitly share them by going into each profile, clicking the ‘Share’ icon and clicking the switch to mark the profile as shared. If you do this, your profile will be visible to (but not editable by) anyone with whom you share the profile URL.


• By default, profiles are private and are only visible to you when you log into the site.


• DNA Painter does not store your raw DNA data itself – just the match segments.


• Our aim is to provide a service that’s useful to the genetic genealogy community and we will never make any other use of your data or sell your information to any third party.5

Nothing to be concerned about there: as long as you don’t share a profile with anyone else, your information is secure — as much as anything is these days. If you are going to share a profile with anyone else, then you need to be very careful about the detail you enter into the information fields. Remember: you can’t share a profile that includes identifiable information about living people unless you have the consent of those living people.

So… how much time did it take me to paint my uncle’s chromosomes using DNA Painter?

Including reading the help and watching the video, less than an eight-hour work-day.

And I can already see, with some unknown matches, just how useful it’s going to be. There’s one set of three new clearly-related (as in share-a-surname) matches that I can pretty well slot into my Gentry line by lining up their segments with what’s been painted.

Now if only DNA Painter had a feature to goose those matches into responding to email…


  1. Help: What is DNAPainter?,” ( : accessed 8 Apr 2018).
  2. Ibid., “Help: Why Would You Use DNA Painter?.”
  3. Roberta Estes, “DNAPainter – Mining Vendor Matches to Paint Your Chromosomes,”, posted 4 Apr 2018 ( : accessed 8 Apr 2018).
  4. See e.g. Sami Edge, “Internet sleuths, DNA link John Doe to Northern New Mexico,” Sante Fe New Mexican, posted 31 Mar 2018 ( : accessed 8 Apr 2018).
  5. Privacy Policy,” ( : accessed 8 Apr 2018).
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