Even if you're only 1% Jewish, the Goyim always know you're a Jew. Rabbi Yaron Reuven tells a story of a Jew who was in the German army, and even though he was fighting along side the rest of the Germans, he was the victim of antisemitism. They told him to eat pig or they would beat him to death and he chose to die rather than eat pig. He was a simple Jew who didn't know he didn't have to die for this mitzvah, but he survived and HaShem blessed him with great wealth and freedom.