I used to think that all boys had short hair and all girls had long hair, since that is typical.
When my sister was really little (even though she is only two years younger than me), she had short hair, which looked very boyish, so I was surprised when my dad told me that she was a girl.
A childhood belief about hair

others believed things like this
- Since the girls name Jackie is short for Jacqueline, I thought the boys name Jack was short for JackalAnon
- I used to think that everybody's hair was black and if you had blond hair, you dyed your hair.— ~_~CoolKid93_~_
- I thought Buckwheat from "The Little Rascals" (1994) was a girl because he had long hair!— Molly
- I used to hold my hand over my hair whenever i left the house and it was windy incase my hair blew away— lisa
- I used to believe that you could curl your hair by twirling a strand of hair wrapped around your finger— Anonymous
- I believed that if you ate a piece of your own hair, a new strand of hair would grow on your head.— Ryo