My family is from the Netherlands and my grandmother was always aware that her grandmother was Jewish but she did not mention it to the family until recently, mainly because of hangover trauma from World War Two and the stress/fear the family suffered from worrying that it would be discovered that her (then deceased) grandmother had been Jewish. I'm not too knowledgeable about Judaism but I know that I've read somewhere before that a person is considered a Jew if their mother was a Jew, and I was wondering if technically I would be considered Jewish? Since I'm directly descended from my Jewish ancestor through my matrilineal line.
Indeed, one is considered Jewish if one's mother is Jewish or if one converts in accordance with Halakhah (Jewish law). See this answer and the "introductory article" cited below for more information.
If your maternal grandmother's maternal grandmother was Jewish, that means:
- Your maternal's grandmother mother was Jewish
- Your maternal grandmother is Jewish
- Your mother is Jewish
- And... you are Jewish!
Mazal Tov (congratulations)! You have just discovered that you are the direct heir of the most valuable, meaningful tradition in the world!
Please stick around MiYodeya and also contact your local Orthodox Rabbi (I personally recommend Chabad).
Here is a great introductory article from Chabad.org about what defines a Jew.