What are X DNA matches on Gedmatch? What does total cM on an X match mean? In this post, I’ll answer these questions, as well as explain:
- The difference between X DNA and autosomal DNA matches on Gedmatch
- How to find X DNA matches on Gedmatch
- How to access detailed shared X DNA information on Gedmatch
Gedmatch is a truly amazing tool, and learning about X DNA matches on the site can help you take your research to the next level.
What is the difference between autosomal and X DNA matches on Gedmatch?
We already know that autosomal DNA is passed down in essentially equal shares from both of our parents. Males and females inherit 50% of their autosomal DNA from their mother and their father, and will share an average of 25% of their DNA with all of their grandparents.
- Autosomal DNA is DNA that we inherit on our “numbered” chromosomes (1-22)
Any given autosomal DNA match can be related to us, therefore, on either side of our family. We will have to do some family tree research to determine whether an autosomal match is on our maternal or paternal lines.
X DNA inheritance is decidedly different, and we can use these unique inheritance patterns to determine how we might be related to our X DNA matches.
- X DNA is DNA that we inherit on our sex chromosome, which is the chromosome that determines whether we are biologically male or female
- Males will have a Y chromosome and an X chromosome, while females will inherit an X chromosome from both their mother and father
Because of how X DNA is passed down, we can use whether or not we match with someone on the X chromosome to determine whether we are related on our mother or father’s side of the family.
What is an X DNA match on Gedmatch?
An X DNA match is a person with whom you share at least one segment of DNA on your X chromosome. We all have at least one X chromosome.
(Males have one copy of the X chromosome, while females have two)
As I mentioned before, males inherit X DNA information from their mothers only. They don’t get any X DNA chromosomes from their fathers.
For example, my father only had one X DNA chromosome. He passed it down to me 100% intact.
This is in contrast to the one that I got from my mother, which is a “recombined” segment (though it doesn’t always have to be) of her two X chromosomes which she inherited from both of her parents. The recombination process is sort of like “mixing” the two copies of the X chromosome to make a new, unique copy made from smaller bits of the originals.
Since I got X DNA from both of my parents, I can’t tell for sure which side of my family my X DNA matches are on. They could be from either my mother or father.
Even so, I do know that even if my X DNA matches are paternal, they can’t be from my dad’s father’s side of the family. He didn’t get any X DNA information his dad to pass down to me.
The same process of elimination can be found on my mom’s side of the family. Even though she got her X DNA from both of her parents, I know that X DNA matches on her side of the family can’t be from her paternal grandfather.
If you happen to be male, you can eliminate one entire side of your family for X DNA matches. Since you didn’t inherit any X DNA from your father, you know that your X DNA matches can only be on your mother’s side.
How to find X DNA matches on Gedmatch
You can find X DNA matches directly on your Gedmatch One-to-Many comparison tool results. These results are also referred to as your list of Gedmatch DNA matches.
On your Gedmatch DNA match list, you will see a heading with two columns to the right that says “X DNA”. The two columns under this heading are “Total cM” and “Largest”.
In the image below, you can see the columns to which I am referring:
As you scroll down through your DNA match list, you can take note of which matches also share X DNA with you. If you see the number zero in this these columns, you can assume that you share no X DNA with those particular matches.
If you are only looking for X DNA matches, you can sort your Gedmatch One to Many list in order to display the top X DNA matches first. Do this by clicking on the heading for the X DNA “Total cM” column twice.
Sorting your list to show the X DNA matches first will display the matches on order of greatest shared X DNA to least. It’s important to note that some people might share X DNA with you and share no autosomal DNA, usually implying a distant relationship.
You can use whether you have shared X DNA, how much you have, and how much autosomal DNA you share with a particular person in order to estimate your potential relationship.
As always, the best way to figure out how you are related to someone is by using thorough family tree information. DNA results can help point you in the right direction.
What does total cM under X DNA mean on Gedmatch?
The”Total cM” column on Gedmatch is the total of the length of shared X DNA segments that you have with a particular DNA match. The length of the largest X-DNA segment and total amount of shared X-DNA shared can be used to help you figure out how you might be connected to your match.
How to compare X-DNA on Gedmatch
You can find X DNA matches from your autosomal One-to-Many list, which is how many people arrive at X DNA matches on Gedmatch. However, the information contained on your One-to-Many results does not include detailed segment data about your X match.
In order to see details about the X DNA that you share with your match, you will need to use the “One-to-One X DNA Comparison” tool. This tool can be accessed from your main Gedmatch dashboard under the “DNA Applications” section, as seen in the image below
Learn more about X DNA
There is a LOT that you can learn about X DNA. For starters, check out these posts:
- Got questions about the X chromosome?
- How to understand Gedmatch X One to One results
- What does no shared X DNA segments found mean?
I hope that this post has helped you understand more about X DNA matches on Gedmatch and how you can use them to learn more about your family tree.
If you have any questions about something that you read in this post, I would love to hear from you in the discussion below.
Thanks for stopping by today!