I'm not an expert either and the quote I gave you is from someone who has traced her ancestors back to 2 x g.grandparents so, obviously more Jewish ancestry than me. However, it still hasn't helped me trace my g.grandfather's origins.
Doing my DNA did, however, prove what I had always suspected that many trees on Ancestry giving my g.grandfather parents had the wrong man (or is that the wrong parents?). One of the people who is directly descended from the supposed mother of my g.grandfather did his DNA too and, not a surprise to me, there was absolutely no match between us. He has now deleted the descendants of my g.grandfather that he had assigned to this other man and I wrote to other tree owners and most of them have also deleted the descendants, so that's one plus.