My grandma got a cat when I was about 4-5 and I figured she must have picked it up off a shelf at the grocery store, like bread or cereal. It never occurred to me that I'd never seen cats and dogs on the shelves there, it just seemed natural.
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 dogs were male and all cats were female. I still call dogs "boy" and cats "girl." — Kelly F.
- I use to believe that cats and dogs were the same species; cats were girls and dogs were boys.— poopcrystals
- When i was younger my grandma told me that the nuts that was on the bread were bug wings, i still ate it.— Matt
- I used to believe that dogs ate cats.— Tom
- I used to believe dogs ate cats— LEADY