23andMe Chromosome Painting is a visualization of how your ethnicity composition is represented across your chromosomes.
23andMe doesn’t always make it easy to find the different features on their website. You can be forgiven if you haven’t actually noticed your chromosome painting.
How To Find Your Chromosome Painting
The link to open your Chromosome Painting is on the Home Page in the section for Ancestry Composition.
Click on the “View Report” link under the DNA Painting heading.
The visualization can be a little slow to display. The webpage is generating it dynamically, based on the breakdown of your ancestry (or ethnicity) composition.
After a few seconds, a long stack of colored lines will appear on the page. This is your Chromosome Painting.
How To Read Your Chromosome Painting
The visualization is laid out as a representation of 22 of your chromosome pairs plus the X chromosome(s).
Men just see one X chromosome. Women, of course, get one from each parent.
What do the colors mean?
Each color represents one of the populations in your ancestry composition.
As you hover over the composition breakdown on the left side of the page, the painting will change to highlight the color of each population. This is a great help if you have lots of small percentages in your breakdown.
What do the hashed pieces mean?
Some of your chromosome pairs have a light-gray hashed portion. This shows the parts of some chromosomes that are not included in 23andMe’s DNA analysis.
There’s nothing wrong with your DNA test. This is the same for all customers.
Focus on the length of the colored segments
If you have several different colors on a chromosome, the length of each section can give you clues to ancestry.
Longer sections point to more recent admixture (ethnicity). This means that you inherited this regional population from more recent ancestors.
Shorter colored sections point to inheritance of these pieces from more distant ancestors going back many generations.
Changing The Confidence Level
When you expand the confidence level link at the top of the page, a new section appears on the page. The link is just above the start of the Chromosome Painting.
The default level is set to the lowest option, which is at 50%.
You can choose to increase the confidence level through increments of ten percent.
By the way, 23andMe refers to this tool as a “slider”. But you don’t grab and slide the highlighted green ball along the diagram. Just click on the circle marking the percentage you want to use.
If you do so, you will probably see the colors that represent lower percentage populations disappear.
What happens is that lower confidence populations are merged into broader regions.
For example, I have a 0.2% assignment of Nigerian ancestry. At 50% confidence level, there is a small section on one of my 8th chromosomes that is assigned a color.
By just going up to 60% confidence level, this section is subsumed into the “Broadly West African” region.
When I move up to 90% confidence level, the “Broadly West African” region disappears from my composition.
Even the “West African” top hierarchy is gone, with the percentages reassigned to “Broadly Sub-SaharanAFrican”.
Which Chromosome Is From Which Parent?
Earlier versions of the Chromosome Painting could only show a single chromosome to represent a pair. So, the colors represented combined inheritance from both parents.
The current version is a great improvement in terms of separating the display into two chromosomes per pair.
However, 23andMe cannot determine which chromosome is from your mother or your father.
Parents from distant regions
My maternal heritage goes back generations in Ireland. My paternal heritage is East African.
So, I can tell at a glance which chromosome comes from which parent. In the picture below, the blue region represents “Britain & Ireland”.
Even though this is quite easy to differentiate, notice how 23andMe isn’t consistent in how it presents the positions of the chromosomes. So my maternal chromosome is the lower half of the 8th pair. While it’s the upper half of the 9th pair.
Testing a parent
If one or both of your parents have tested with 23andMe, then you will have an advantage here.
You do need to take action to connect your DNA with your parent’s account. If you do so, 23andMe will put your maternal chromosome in the upper position and your paternal chromosome in the lower position.
Beware of mistakes
Some customers have reported that 23andMe has assigned populations incorrectly to a mother or father’s chromosome.
Chromosome Painting Vs Chromosome Browser
This Chromosome Painting is different from 23andMe’s Chromosome Browser.
The Browser lets you examine the positions of the shared DNA that you have with a specific DNA relative in your list.
We have a separate article on using 23andMe chromosome browsers for triangulating your relatives.