As a small child I was absolutely convinced that people in the olden days lived their day to day lives in black and white, and that they walked slightly faster than we did today (assuming a frame rate thing?).
I'm gonna put this one down to my understanding of how TV worked as a ten year old. Everything before colour TV was black and white... therefore everything was black and white. Makes perfect sense.
What about you?
I used to believe that only women drank tea and only men drank coffee (owing the the fact that my Mum only drinks tea and my Dad only drinks coffee).
I was a bit weirded out when I first encountered a friend's mother drinking coffee.