A childhood belief about history

When I was young, I thought that the world really used to be in black and white, just like in the old TV shows and the black and white pictures in my grandmother's photo albums. I was very glad that I hadn't been born until after the world turned to color. At some point, I asked my mother when exactly the world had become color; I knew that she had been born before a lot of those black and white TV shows were on the air, and she is in a lot of those black and white pictures, so I assumed she must remember what it was like to be black and white and that she would know exactly when the change happened. That was when I learned about film. The bizarre thing is that we had a small black and white TV, and I could see perfectly well that shows that were in color on the big TV were in black and white on the small TV. I don't know why I never put 2 and 2 together.