I found my mother's "Alien" card when I was 5 years old. I actually believed my mom was an alien, until I finally asked her and she explained that she was an immigrant.
A childhood belief about nationalities

others believed things like this
- I thought the ball-headed person in the Bic logo was an alien and communicated using alien-like noises.Anon
- Oh oh, I'm an alien, I'm a little alien...
Legal maybe?— Marina - I got given a box of slime marked "alien puke" and asked if E.T. was all right.Anon
- I used to think that my cat was an alien that had come to teach me how to be good!— laz
- I used to belive that my teacher was a alien unfortunately this was true mum and said. — peter
- I used to think that green poop ment you were an alien.— fartcheeks