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I recently received results from a Y-DNA test between my uncle and a cousin. They are 4th cousins, 1x removed. I would expect them to match very closely as Y-DNA does not change much, however, at 12 markers they differ by 1 step, at 25 markers there are 3 step differences and they drop off as a match at this level in Family Tree DNA. By 36 markers there are 5 differences.

Does this seem a bit odd?

I was expecting the match to be much closer between 4th cousins.

I just checked, and most appear to be multi-copy markers, which maybe would account for it? The differences occur at DYS385 (the first number), DYS459 (the first number), DYS464 (the first number), CDY (both numbers). But I would think FTDNA would take that into account, and uncle/cousin aren't showing as a match beyond 12 markers.

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    Can you confirm that they're related to each other through the male line of descent?
    – user104
    Commented Jan 25, 2017 at 11:59
  • Absolutely. My cousin's great grandfather and my uncle's great great grandfather were brothers. Both lines are well documented, so I'm not quite sure why there are so many different steps in just a few generations.
    – Hammy
    Commented Jan 25, 2017 at 12:28
  • Not trying to start anything, but the cousin's great grandfather and uncle's great great grandfather are suppose to be brothers. Maybe there is some family info one does not know as families often keep secrets. Just saying. I am getting into this, so I may be just talking out of place. I know when helping friends, we have found this at times. When we investigated more thoroughly we found out what was suspected. Like I told a person that heard about a friend's family situation as well, sometimes you just be quiet and not ask questions (unless you are ready for the answer).
    – dawn
    Commented Jan 27, 2017 at 20:10

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The results are OK. Really, the mutations are statistical matter. So sometimes there is no difference between father and son in STRs, or there maybe great difference because several mutations happened simultaneously. We need to know your reasons and targets to advise something.

For example, it is good idea to make FamilyFinder (i.e. autosomal) test, because both persons mentioned before will share significant part of autosomal DNA.

If we talk about Y-DNA, SNP testing is much more precise in terms of relationship proving than Y-STRs. But the good SNP testing is much more expensive.

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