I used to believe that you had two different colours of blood, Red and Blue because I was so sure I heard my babysitter say that.
A childhood belief about general

others believed things like this
- when I was young, I heard that blood had iron in it. I thought blood was red because it was rusty.— Hunter
- I used to think that blood was blue until it touched air.— paetrw
- I thought the blue veins in some cheeses were actually blood vessesls!— Helen
- Eifel 65 - Blue
I'm Blue (if I was green I would die...)
[I'm blue, da ba dee, da ba di.]— Matt - i used to believe everyone saw different colours but just described the same.Anon
- I thought that the Chewit wrappers were different flavours as they were different colours like the sweets— Helen