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Trying to figure paternal relationships from several generations ago

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  • Trying to figure paternal relationships from several generations ago

    I apologize if this has been answered elsewhere. I've been doing a lot of reading but it is not clear how easy it would be to derive from a Y-DNA test what I am trying to get.

    I have an ancestor from 7 generations ago (Johanes Jacob Brumbach/Brumbaugh b.1726/d.1799) and there is debate among those who researched him if he is the brother of another famous Brumbach/Brumbaugh from that time frame (Johanes Heinrich B.) More info here:

    I have uncles and cousins who should be direct male descendants of J. Jacob Brumbaugh. If I can find a direct male descendants of Johanes Heinrich Brumbaugh that are willing to take the appropriate test can I figure out the exact relationship between these two men?

    I see on here: that 37/37 markers gives you a 95% probability that the relationship was within 7 generations and 66/67 gives 95% within 9 generations. The last 7 generations of both families is fairly well documented. I guess the best result I could hope for is a high number of matching markers, but could I distinguish between if these two men were brothers or first cousins or second cousins?

  • #2
    Best bet is to recruit as many of these descendants as possible to test at the highest level possible (given the available funds -- theirs or yours). Exact relationships can't be proven this way, but it may be possible to place some limits on the feasible relationships. If all of these do in fact descend from the same Brumbach family, there is a good possibility that one or more branches have accumulated at least one inherited mutation on the Y chromosome. In some other families (e.g., descendants of Deacon Edmund Rice, Buchanan family, and many others), it has been possible to work out a "haplotree" for these mutations that sheds light on the way the different branches must connect. Sometimes descendants of enough of the branches can be found that it becomes possible to pinpoint the exact generation where a mutation arose. Among the Edmund Rice descendants, it has even been possible to identify branches that have ended up with different surnames through various accidents of history -- a remarkable story worth studying for the insights it may provide on how genetic evidence can inform genealogical research. Note that there are two kinds of data available: STR scores (Y-37 and similar tests up to Y-111) and SNP scores (Big Y and similar). SNP scores are probably better for this kind of analysis if you can get them, but a lot of useful clues have come from STR's.


    • #3
      Thanks. That makes sense. My take away from what you said is I would need people from outside these two branches but have descended from the same Y-DNA and look for a common mutation (in these two branches) that isn't present in the other branches. It sounds like a significant undertaking and would need an awful lot of people to really nail anything down.