I'm the administrator of a Y-DNA project for a Jewish surname (Heimlich),
which is not too common. Most of them are of Hungarian origin and trace
back to NE Hungary in the early 1800s. But good "paper trail" is lacking
before about 1850.
Some of the descendants have been working on the genealogy for forty years
or more, but because of the spotty paper records, were unable to determine
whether all the Hungarian Heimlichs shared a single male ancestor.
We first made a list of all known branches (there turned out to be 29 of
them), and then set out to test one descendant of each branch. So far, we
have seven results: three of them are E1b (and match each other closely).
Three are R1a and Levites. they match each other also, but less closely.
The seventh one is Q1.
My point is that you can acheive good results by careful and targeted
Y-DNA testing. And when you get a match, you know you really have a