In this article, I will help you understand One-to-Many results on Gedmatch. By the time you are done, you will feel comfortable reading your results.
One of the most useful DNA analysis tools on Gedmatch is the One-to-Many tool. For first time users, however, looking at this giant spreadsheet-type list of information and knowing what it can tell you may seem overwhelming.
Gedmatch is not a DNA testing company, and so in order to use the site and get access to One-to-Many results, you’ll need to take a DNA test. If you haven’t yet taken a DNA test, you can learn about the different tests available here: What is an Autosomal DNA Test?
What do the columns in One-to-Many Results mean?
Do you want to know what each individual column means? While some seem self-explanatory, others might be new to you.
Working from left to right, I’ll go through every column here to explain what it means, and potentially what you can do with the information:
Kit Nbr (abbreviation for kit number)
This is the number assigned to the DNA raw data file that is submitted. You have your own individual kit number, and you can use the kit numbers of other users of the site in order to compare your DNA against theirs.
This is a skinny little column to the right of the kit number, but it can be important. There isn’t necessarily a better/worse number.
If a number matches yours, however, then the results are more accurate. I wouldn’t worry too much about this test type number, but if you have a weird result, you might try checking to see if your match has the same type as you.
If you press the “L” in the list column, you can see all of the DNA kit matches (one-to-many) for that individual. This can help you get an idea of how you might be related (though there are other tools you can use to do this).
You can choose three or more test kits to run some additional utilities. Choose them by clicking this box.
This is obvious, but it is helpful to know if your DNA match is male or female!
This is one of my favorite new features of the One-to-Many too. Many people have not uploaded a family tree to the site, but some people have.
If you see a link to a GED or a Wiki, you can click through to learn more about your match. Hopefully, you will learn something about how you are related and more about your ancestors.
Some DNA testing companies offer higher resolution tests that can determine a Mitochondrial DNA Haplogroup. This type of DNA is passed down through the maternal line almost identically for thousands and thousands of years.
Don’t worry if your test doesn’t tell you yours. If it does, however, there are ways in which it can be useful in determining whether what you know about your family tree is correct.
Both men and women can have a mtDNA Haplogroup
Similar to the mtDNA test, a Y DNA test can identify the paternal line going back thousands and thousands of years. Just like the mtDNA test, if you share a Y DNA haplogroup with someone, there isn’t any way to know whether your common paternal ancestor was two generations ago (like a grandfather) or 30 generations ago.
From a genealogical perspective, it can be helpful in verifying paternal lines. Only available to males, this test is also interesting from an intellectual standpoint.
This is handy feature. If you click the linked “A”, you will immediate open up a new tab with the One-to-One comparison tool already filled out for you.
Gedmatch recommends that you perform the One-to-One comparison before you contact any of your matches, just to verify shared centimorgans and estimated genealogical distance. If you get the same or similar results with the One-to-One tool, then you should definitely consider contacting your match!
Total cM (Autosomal)
This is the total number of centimorgans that you share with your match from segments above 7 cMs in length. This “total” number could be made of up from a few dozen segments to only one segment.
Many people share really, really tiny 1-4 cMs with each other, but those are just “coincidental” (the technical term is identical by state). Only larger segments, usually above 5 cMs are reliably “identical-by-descent”, meaning you share this segment because of a common ancestor.
Largest cM (Autosomal)
This is a helpful bit of information. Typically, the larger the DNA segment (measured in length: cMs), the closer the relationship.
For example, I share a 281 cM segment with my mother. With my father’s first cousin, our largest shared segment is only 62 cMs. With my two second cousins once-removed, I share 55 and 31.
The smaller the largest segment, the further back the most recent common ancestor, generally speaking.
This is the estimated number of generations that you will have to go back in order to find your common ancestor with the DNA match. This is only an estimate, and it is based on the average DNA shared between people of different relationships.
It is most accurate with closer relationships. The further back your common ancestor is, the less reliable this estimate. Still, it is handy to know as a reference.
If you click on this linked X, you will automatically open up the One-to-One X-DNA comparison tool. This is where you can see the details about your X-DNA match, and try to figure out how you are related.
This information is best used for advanced users.
Total cM (X-DNA)
This is similar to the autosomal total cM, but instead this number only counts the total amount of X-DNA you share. We only have one X chromosone, so the number of centimorgans that you can share with a match will be much smaller, with a maximum shown in this column of 196.1 cM.
This information is best used for advanced users.
Largest cM (X-DNA)
In this column, you will see the length of the largest segment of X-DNA, measured in centimorgans (cMs). This helps you figure out the distance in the relationship.
Most of the time, the length of the biggest segment will match the total number of cMs, but not always. This information is best used for advanced users.
This is the name associated with the test kit. If there is an asterisk, it means that the name shown is an “alias”.
Sometimes the alias used is a screen name or initials. People usually do this to protect their privacy.
This is the contact e-mail provided by the person who submitted the DNA file. Sometimes the e-mail belongs to someone who is administering the kit for them, and other times it belongs to the person who the DNA sample belonged to.
I hope that this post helped you understand a little bit more about all of the details shown in the Gedmatch One-to-Many comparison tool. Gedmatch is a great website that is a nice compliment to all that you’ve learned from your DNA results and from building your family tree.
I highly recommend building at least a basic tree on your favorite online platform. I use Ancestry because it’s easy to add people and records, but there are many other places and ways to do yours.
Do you have any questions about your Gedmatch One-to-One results? Please feel free to ask me here in the comments, I will respond as soon as I see your comment. Thanks so much for reading my post, and for stopping by.