What is XDNA? We have answers! And so does your XDNA itself. XDNA can be used for genealogy, whether you’re a man or a woman. Sort your DNA matches using XDNA to help you with your family history.
We usually talk about THREE kinds of DNA tests available for genealogists: Y DNA, mtDNA, and autosomal DNA. However, there is a fourth category of DNA that can prove useful in your genetic genealogy searches. It can’t be tested on its own, but is produced as part of an autosomal DNA test. It is the XDNA.
Two DNA testing companies report XDNA information: Family Tree DNA (the Family Finder test)* and 23andMe. Check out this quick video tutorial and the article below.
What is XDNA?
Y DNA and XDNA determine biological sex:
- Genetic males have one XDNA from their mom, and a YDNA from their dad.
- Genetic females have two copies of the XDNA, one from each parent.
Because of this association with a man’s mother’s side, XDNA is often confused with the mtDNA, which is ALSO associated with our mothers. However, these are two very different kinds of DNA with very different inheritance patterns. The mtDNA is passed from a mother to all of her children, and then only the females pass it to the next generation. For this reason, the mtDNA you have is the same as your mother’s and your 10X-great grandmother’s (which still blows me away every time I think about it!).
The XDNA, on the other hand, has a very tricky inheritance pattern. Here’s what it looks like for both women and men (the orange boxes in the fan chart are the female ancestors, and the green are the males):
XDNA inheritance pattern for a woman
XDNA inheritance pattern for a man
What testing companies report XDNA?
While all companies are testing XDNA, you’ll only get XDNA reports from two tests: 23andMe and FTDNA’s Family Finder test.* At Family Tree DNA, they even allow you to filter your results by those matching your XDNA:
You can also see XDNA results by transferring to GEDmatch, although the site is not something I generally recommend. As shown below, you’ll see your XDNA matches along with information about how much DNA you share.
XDNA testing for men v. women
Because a man receives XDNA only from his mother, his father’s side of the pedigree is completely blank. This actually helps XDNA match analysis in many cases for men, as any match who is sharing XDNA should only be related on the maternal side, providing an easy way to identify maternal side matches. (But be careful, as not all matches on a mom’s side will share XDNA with you.)
Women, on the other hand, are more complicated. Since they receive one XDNA from each parent, they have XDNA from ancestors on both sides of their pedigree chart.
While XDNA might be slightly more useful for men, it is still very useful for women. Looking at the charts again, you can see that there are a lot of white spaces for both men and women. Looking at the white spaces on an XDNA match’s fan chart will immediately tell you all the ancestors that DO NOT connect you and your match, leaving only a handful of ancestors that could be connecting you.
Apply DNA to your family history
If you have unknown DNA matches in your match list, then you need our free guide, Finding Ancestors with DNA. Together with the tips in this article, this guide covers everything you need to know about getting getting started with your DNA matches to find an unknown ancestor.
I think the xDNA can be helpful. I will have to examine further. And, since the test has already been done if you did FF, there is no extra cost! Thank you for explaining this!
Interesting!
Why do you not recommend Gedmatch site? Thanks.
Hey Patricia, here are my thoughts on Gedmatch: https://www.yourdnaguide.com/upload-to-gedmatch.
FamilyTreeDNA was the second site I tested at. (The first was the National Geographic site.) At the time, there was no “Family Finder” feature and I think it just did YDNA and mtDNA testing. I was pleased to finally learn here what the X Match meant and to try out that feature. Lo and Behold I had multiple matches, but only one of them had a shared DNA over 11 cM. I already knew her and have her in my tree. Does this mean the X DNA feature is of no use to me?
Hi Patricia, our rule of thumb is that matches should share at least 10 cM on the X chromosome to be useful in finding connections. The good news is that new people are joining DNA testing databases everyday, so you never know when a new XDNA match will show up on your match list. I would recommend working on another line for a while anc checking back in on your XDNA in a few months to see if anyone new has come up.
Where on these sites do you find the amount of shared X centimorgans please
On FamilyTreeDNA, hover at the top left over “Results & Tools,” then hover over “Autosomal DNA” and click on “Matches.” On your match page in the “Detail View” tab, the column on the far right will list any shared X cM’s. On the “Table View” tab, the X Match column will be closer to the middle.
Thanks! I am part of the YDG Study group, and was not yet aware of XDNA. After watching your short video this morning, I was able to identify a 3C 1R on FamilytreeDNA in 10 minutes.
How do you get a XDNA report on 23andme?
They don’t have an XDNA report, though 23andme does test your XDNA as part of their autosomal testing, so you can see matches who share your XDNA. You can click the following link to view your maternal haplogroup report, which is based on your mitochondrial DNA. https://you.23andme.com/reports/maternal_haplogroup/
I decided to go through my X matches on FamilyTreeDNA to see if I could figure out which ancestors my XDNA comes from. I have a pretty good idea, based on how I’m related to my matches, but I am curious about a couple of results.
I have a cousin on my mom’s side who matches me, but she would have received her X DNA from her father, and he would have received his X DNA from his mother – a woman who is not, so far as I know, related to me at all.
I have a cousin on my dad’s side who shares almost twice as many cMs in our X DNA match than I share with my brother (who also tested with FamilyTreeDNA). I’m curious about how that could be.
Do the X chromosomes recombine when they are passed down by mothers to daughters?
Also, how many cM are tested on the X chromosome?