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No matches? No testers!

It’s a common complaint in one very common group:

“I don’t have any close YDNA matches!”

The speaker in this case, as in so many cases, is German-American.

Roughly one in seven Americans has some German ancestry,1 though a far smaller group will have the German line where it would have to be to show up for YDNA testing: remember that YDNA is the kind of DNA that only men have and that’s passed down from father to son to son (and so on) largely unchanged througyh the generations.2 So the German line would have to be their father’s father’s father’s line.

In this reader’s case, it was that line: his great grandfather came to the United States in 1880 from Germany, and the YDNA line comes down through his grandfather and father to him.

So… why doesn’t he have any YDNA matches closer than a genetic distance of 2 in a YDNA-37 test? Is it reasonable to suspect, as this reader does, that his youthful great grandmother was fooling around on his elderly great grandfather (“I suspect a Drummer, or salesman got close, while old (great grandpa) was out in the fields”)?

First, some terminology. The particular DNA sequences being looked at in YDNA testing are called short tandem repeats (STRs), and they’re patterns of DNA code that form sequences and where the sequences are repeated a number of times at those particular locations on the Y chromosome.3

Those particular locations are called markers: the genes or DNA sequences with known locations within a chromosome that make them useful for comparing one person’s DNA with another.4 In the case of YDNA testing, it’s the STRs — those short tandem repeats — in a number of locations.

How many of those particular locations are looked at (12, 25, 37, 67 or 111 if you’ve tested at Family Tree DNA) tells you the level of YDNA testing that was done, in short that are the markers being reviewed.

The genetic distance reported is the way the DNA testing people describe the differences, if any, between the markers reported in one person’s DNA results and those reported in a second person’s results. “A genetic distance of zero means that there are no differences in the two results and there is an exact match.”5 If the genetic distance is small enough, the two people are considered a match, meaning they share a common ancestor.

The lowest possible level, in older tests not even readily available any more, looked at only 12 markers and, at that level, in some very common populations, a perfect match basically means nothing more than yep, you and all of your matches are in fact European males.

YDNA testing at 37 markers is pretty middle of the road, and a genetic distance of two in a Y-37 test — where there isn’t a common surname between the people tested — may only be suggestive of a genetic relationship within the time frame when we might be able to find genealogical records. The more markers tested and the closer the matches, especially if they share a surname, the higher the chances that the people are related, and related within a recent time frame.

Got that? If you need more, check out the post Understanding the Y match.

Now… here’s the catch to all of this: you can’t be matched to somebody who hasn’t tested.

That’s something we tend to forget when we look at our matches. If the population we come from isn’t doing a lot of testing, we’re not going to have a lot of matches.

And… sigh… Germans aren’t testing in anything near the numbers that other groups are.

There are a lot of reasons for this. There’s a cultural resistance to DNA testing that stems from the history of eugenics by the Nazis.6 There are strong privacy laws in place in Germany as well, though DNA tests for genealogy are perfectly legal,7 and Germany isn’t even on the list of countries to which AncestryDNA will ship a DNA test kit.8

Since this reader’s great grandfather came to the United States in 1880, it likely means that any representatives of that male line who are alive today are still in Germany. That would be, for example, the grandsons or great grandsons of this great grandfather’s brothers or male cousins.

So the bottom line is… no, it’s not reasonable to believe that the reason why the reader doesn’t have close matches is that Great Grandma was fooling around in the United States. It’s much more reasonable to think that the reason why the reader doesn’t have close YDNA matches is that other men from his family line haven’t yet tested.

Now this may change in the future. Family Tree DNA does sell DNA tests in Germany, and there are YDNA projects for Germans and German Americans with thousands of members.

Autosomal DNA testing is igniting interest in this kind of testing for genealogy around the world and may help break down some of the resistance to testing. There’s a company called LivingDNA that’s trying to break through the German resistance to DNA testing and create a database of autosomal DNA test data for Germans with what it calls its German DNA Research Project and that holds great promise. And, of course, autosomal testing now could link the reader to cousins who descend from other parts of that German family tree — from females who did come to America, for example.

But for now… the real problem with having few YDNA matches isn’t likely to be that Great Grandma was fooling around. It’s that you can’t be matched to somebody who hasn’t tested.


  1. Roughly 46 million of America’s 321 million residents report German ancestry. See “People reporting ancestry,” 2015 American Community Survey 1-Year Estimates, U.S. Census Bureau ( : accessed 2 July 2017).
  2. ISOGG Wiki (, “Y chromosome DNA tests,” rev. 4 Dec 2016.
  3. ISOGG Wiki (, “Short tandem repeat,” rev. 31 Jan 2017.
  4. See Emily D. Aulicino, Genetic Genealogy: The Basics and Beyond, Kindle edition (Bloomington, IN : AuthorHouse, 2014), Appendix F: Glossary, “marker.”
  5. ISOGG Wiki (, “Genetic distance,” rev. 31 Jan 2017.
  6. See DNA and Eugenics in Nazi Germany, Holocaust Museum & Education Center of Southwest Florida ( : accessed 2 July 2017).
  7. See the discussion at “DNA tests available in Germany,” Ancestry suppport forum ( : accessed 2 July 2017).
  8. See Jessica Latinovic, “AncestryDNA Now Offered in 29 New Countries,” Ancestry blog, posted ( : accessed 2 July 2017).
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