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What Does and Doesn’t a Y DNA Match Mean?

Roberta Estes

It’s easy to forget how foreign this landscape looks to a newbie, but the newbies are our next generation genealogists and genetic genealogists.

This week, someone e-mailed me who had tested at Family Tree DNA and asked how to contact their Y DNA match they had found in a project that I manage.  I thought that was a very strange request, since your matches are on your personal page along with their e-mail addresses, so I asked for the name on their kit and their kit number so I could take a look.

As it turns out, they had no Y DNA matches on their personal page, so they were hunting for matches elsewhere.  They had joined the haplogroup E1b1a-M2 project and it’s there that they found their “matches” that they were asking about.  I commend their tenacity in hunting for matches and finding them in a project, even though they weren’t exactly what they thought.

The kit number here is 343629, Lewis.  You can see in the screen shot from the haplogroup E-M2 project page that they don’t match anyone exactly at 12 markers, and their closest match is to Harris above their entry, and they have 3 mismatches at 12 markers.

As it turns out, Lewis and Harris didn’t qualify as matches, which is why they weren’t displayed on their personal match page.  This explains why kit 343629 was asking me how to contact their “matches.”

Family Tree DNA has set up match thresholds.  For someone to be listed as your match, they need to have no more than the following total number of mutations difference from your results.

Markers in Panel Tested Maximum Number of Mutations Allowed
12 0 unless in a common project, then 1
25 2
37 4
67 7
111 10

The reason for these thresholds is that DNA mutates at an “average” rate and for someone to have more than this number of mutations in that marker range means, generally, that the match is too far back in time to be genealogically relevant.  For people who do have matches, you can utilize Family Tree DNA’s TIP calculator to obtain an estimate of how distant the most recent common ancestor (MRCA) might be from you and your match.  I wrote about the TIP calculator and the MRCA both, so refer to those articles for more into on those tools.

The next question this person asked is, “How do you tell which markers indicate someone as a close cousin?”

The answer really involves several aspects or DNA testing, and I’m going to answer their question here, in pieces, so that everyone can benefit.

  1. In general, finding family via the Y markers is not about “which markers” as much as it is about the number of matching markers. If you share a common ancestor, the DNA of that man’s descendants will accrue mutations over time. If the common ancestor is before the advent of surnames in the culture in which they resided, then the surnames may not match, but the common ancestor still existed.
  2. In general, 12 markers is not sufficient to determine a common ancestor, although you can rule out common ancestors in a genealogical timeframe, generally accepted to be 500-800 years, by high numbers of mismatches caused by mutations. I would suggest this person test at higher markers because sometimes people do pick up matches at higher levels where more mutations are allowed, especially if the mutations happened, for some reason, in the lower panels but few happened in the higher panels. I do see this when writing the Personalized DNA Reports for people, not often, but it does occur, especially at 111 markers.
  3. You cannot necessarily identify a “close cousin” or any specific relationship utilizing Y DNA testing alone, especially at low marker levels, such as 12 and 25.  Although if someone matches you on all 111 markers, there is a very good chance that you share a common ancestors in just a few generations. What the traditional Y test (meaning not the Big Y test) does confirm is whether or not you share a common paternal ancestor and then it’s up to genealogy and autosomal testing to determine how close that relationship might be. The number of matching Y markers can provide hints and generalities through the TIP tool, but nothing more.
  4. For this individual, in addition to upgrading beyond 12 markers, I would recommend that they take the Family Finder autosomal test because that will provide them with a list of cousins on all of their lines, not just their Y line. Based on their earlier commentary, they are looking for all family, not just their paternal line. If you have Y matches and autosomal matches, through the Advanced Matching tool on your Personal Page you can see who, if anyone, is a match to you on both.
  5. However, all of this said, the combined pattern of Y markers, not individual markers, determine the match or non-match, and it is your personal DNA signature. Think of it as a song and the markers as notes in your own personal DNA song. Given that mutations arise in each person’s line, sometimes the various DNA mutations are rare, and those rare markers together can be utilized to determine how closely one might match someone else, especially if the surnames don’t match. I see this often in African American descendants of slaves because surnames weren’t adopted until after the Civil War ended in 1865. Often the 1870 census is our first opportunity to find these families with a surname, and sometimes they subsequently changed their surname.

One of the things I do for my customers as part of a Personalized DNA Report is to complete a profile for them of the relative rarity of their DNA by marker.  Please note that I don’t do DNA reports for people who haven’t tested at least 37 markers because I don’t have enough information to work with.

In the case of this individual, I compared their 12 markers in my database of haplogroup marker frequency with the following results.

Values under 25% are bolded, as they are rarer values and the combination of these rarer values are likely to be your own personal family line rare marker DNA signature.  Said differently, you are more likely to be more closely related to those who carry this rare marker signature than those who don’t.

This person has 6 out of 12 markers that are relatively rare.  Normally, one would expect no more than 3, so this is likely why they have no matches.  This is a good news, bad news thing.  The bad news – no matches today.  The good news is that these rare markers value, combined, are a wonderful personal filter that eliminates matches by convergence.  So, someday, when they do have a solid match, it will be relevant and not just because they have all common markers.

And now for the next question.  How can you obtain your own list of marker frequencies?  Obviously, you can order the DNA Report for $349, or if all you want is the marker frequencies, you can order a Quick Consult for $100 and can obtain all 111 of the Y marker frequencies for any one kit.

Guarantees

Most people just want an answer.  I fully understand that.  Me too, but often, that’s not how DNA testing and genetic genealogy as a whole works.  So the question, “What test can I take to give me the answer?” really doesn’t have a solid, works every time, answer.  There is no absolute, no guarantee.  Sometimes, depending on the question at hand, a regular Y DNA test will do exactly what you want.  Other times, like in this case, not so much.  But you won’t know until you test and there is no way to predict an outcome.  Testing may provide the answer in spades, immediately, and it does sometimes.  Other times, you get a puzzle piece with a fortune cookie note that says ”you will undergo more DNA testing.” The answers are tied to DNA testing, yours and other peoples, traditional genealogy research and sometimes, luck.  But it has been my experience that those who work the hardest, test most thoroughly and dig the deepest are most often the ones who experience more occurrences of “luck.”  Keep digging.

As Louis Pasteur said, “Fortune favors the prepared mind.”  Not nearly as eloquent as Dr. Pasteur, my old Hoosier farmer Dad would have said, “apply a little more elbow grease.”

I hope this has helped to clarify what a Y DNA match actually does and doesn’t mean, and how to take the next step in finding your family.

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