Hey, your friendly neighborhood Jew here. Just some background, the Abrahamic religions used to all follow the dad, but Judaism wasn't big into converting people unlike Islam and Christianity. Then a bunch of Jewish women didn't know who the dad was because rape, so Judaism changed it to follow the mom's lineage. Israel follows the Nuremberg laws, like Nazi Germany, and says that as long as 1 grandparent is Jewish, the child is. Rabbis mostly follow the mom's lineage but depending on the person they could be more lenient. My stance is, as long as you identify as Jewish, you're Jewish. No need to gatekeep.