When my sister was 5, my mother gave each of us kids a Siamese kitten. Knowing that my sister was a) a potty-mouth and b) completely naive about pets, I managed to convince her that Siamese cats learned to say a few words as they grew up, and warned her never to swear around the kittens for fear they'd start doing it too.
I thought she would believe me for a week at most, but the kittens became cats before they ever heard a dirty word from her.
A childhood belief about cats and dogs

others believed things like this
- My sister and I thought cats and dogs were the same animal, the dogs were male and the cats were female.— Paul
- I used to believe all cats were female. It completely shocked me when I learned otherwise.— Billy
- My sister's friend thought cats were just small dogs when she was younger.— Richard Davies
- I alwaysused to think white cats were girls, and black cats were male ...— Smiley Face
- I used to believe that the cats eyes in the road...reflectors...were the eyeballs from real cats.— Liza P.
- I liked cats so much I wanted to be a Vet when I grew up, but, I thought they couldn't eat meat.
— Tanya