How is Genetic Distance calculated?
Why do my matches have so many different surnames?
Are all of my Y-DNA matches in the database shown?
The Y-DNA Matches page shows your relevant matches in the database who have signed the release form and are potentially genealogically relevant. If you have not signed the release form, or if you have opted out of matching, you will not be able to see any matches. Likewise, it also does not include test takers who have not signed their release forms, or have opted out of matching.
Y-DNA Match Limits
On the Y-DNA Matches page, relevant matches are shown. Each matching level has a different upper limit for Genetic Distance. Each limit reflects the number of marker differences within those markers only.
For example, you may have a GD of 2 with a match at the 37 marker level, but a GD of 4 at the 111 level if those extra two mutations are found outside of markers 1 through 37.
We feel that a genetic distance greater than these limits reflects a common ancestor outside of a genealogical timeframe. The GD listed at These limits are:
Y-12 Matches - Only matches with a GD of 0*
Y-25 Matches - Matches with a GD up to 2
Y-37 Matches - Matches with a GD up to 4
Y-67 Matches - Matches with a GD up to 7
Y-111 Matches - Matches with a GD up to 10
* For people in our database who are members of a group project you are also a member of, this limit is increased to 1.
Should I contact my matches?
Yes, you should contact your matches. Once you have Y-DNA test results, contacting your matches is the next step in using your DNA for genealogy. If you share a surname or match at 37 or 67 markers then your combined research efforts may lead to new genealogical discoveries.
Why do I match men with different surnames?
There are two reasons you may have a Y-DNA match with someone with a different surname. It may be that your connection is from a time before surnames were in common use. This is especially likely for groups where surnames were often not adopted until the most recent 100 to 200 years, for example, Scandinavians and Jewish populations. Another reason for surnames not to match is that there has been a surname change in genealogical times. That could be in either your match's or your own line.
The main place that you will see matches with many different surnames is the Y-12 marker matches section. The time to a common ancestor for these matches may extend beyond genealogical records and the adoption of surnames.
If you continue to match others outside your surname at the Y-37, Y-67, and Y-111 marker levels, then there is likely to have been a surname change within the genealogical time frame. Common causes for this include deliberate name changes and adoptions. For those matches at a higher number of markers (Y-37, Y-67, and Y-111), contacting your matches is the best way to learn more.
Why do I match men with a surname from my mother’s side?
As the Y chromosome is inherited exclusively from one's father, matching men with a Y-DNA test who share your mother's maiden name or another surname from her lineage may be a coincidence. However, should you continue to match these men at higher levels of testing (Y-37, Y-67, and Y-111) then you may wish to investigate the possibility of an adoption or name change in your family.
I match men with the same surname as mine. What does that mean?
When you match men with the same surname as yours (or a variant) on a Y-DNA test, it means that you have potentially genealogically relevant matches. The best way to find out more is to contact your matches.
Why do I have so many Y-DNA matches?
Having many Y-DNA matches means you have a more common Y-DNA signature (haplotype). This can mean that your lineage has survived and reproduced well. As a result, many people share the same signature. Testing additional markers (Y-37, Y-67, or Y-111) will refine your list of matches to those that are genealogically relevant, meaning those with whom you share a common ancestor in 1 to 15 generations.
Why don't I have any Y-DNA matches?
If you do not have Y-DNA matches, you may be the first person with your Y-DNA signature (haplotype) in our database. This means that no one else from your lineage has tested. As the database grows, you will continue to be compared against new results, and you will be notified by email of any new matches.
What Information is shared with my matches?
Self-reported information as well as shared genetic information are shared with matches. You can tailor what information is included, and read more about what information is shared here.