Judaism traditionally holds that the Jewish identity can only be passed down through one's mother, which is referred to as matrilineal descent. If only one's father is Jewish, which would be patrilineal descent, then they are not counted as being Jewish.
This, in turn, is something that most Jewish Israelis agree with, with 70% saying patrilineal descent is not valid for conferring Jewishness.
By contrast, 26% of Jewish Israelis do consider patrilineal descent as valid, while 4% don't know.