For some weird reason, I've been mistaken a bunch of times for being Jewish, and have had to "come out" to multiple people on different occasions. (So far as I know, there's nothing Jewish in my family tree).
The weird thing is, it's often been Jewish people who thought I was Jewish. Even when I was with a cousin of mine who's the most stereotypical-looking midwest Norwegian-American you can think of. I guess I just have an... atmosphere?