Re: was my great-grandmother Jewish? #general
If your GGM was born in a Christian family, and converted to Judaism, she it totally, thoroughly Jewish according to traditional Jewish law, and DNA knows and shows nothing about it.
If your GGM was born to a Jewish father and a non-coverted gentile woman, she is not considered Jewish according to traditional Jewish law -- no matter how much "Jewish" DNA she has.
Personally, I find it rather jarring to hear people talk of Judaism as though it were a DNA issue. We know who thought being a Jew is a racial issue, and it was not the ancestors of those of us who consider themselves Jewish.
DNA can indicate family relationships, or belonging to certain geographical group. I know Jews from Marrocco, Kurdistan, Ethiopia - since when is being a Jew related to having come from Central Eastern Europe?
So, some questions you should ask yourself about your GGM, that have nothing to do with DNA: