I think I was about eight or nine when I discovered that not everyone 'sees' names in colour.
I can't even really remember what lead up to this revelation, but I do recall that I was very surprised that the rest of my family didn't also 'see' the colours.
Until then I had just accepted that it was normal. Whenever I heard a name I would see it in a colour. My own name, Elaine, was always red, David was a particular blue, George was green, etc., etc.
Oddly enough it didn't work with words in general, just names.
At first I think my parents thought I was making it up and would ask what colour is this name, or that name. Gradually they accepted that I was consistent in my answers. They would almost trot it out like a little party game for a while.
Over the years this sensation, known as synesthesia (a perceptual condition of mixed senses) has faded, although I still have echoes of it.
It still affects me when I am relaxed, eyes closed, and something makes a noise. Then I get a visual impression of (usually) zig-zag lines and assorted colour according to what sort of noise it is, and how loud it is.
What has made me do a post about this odd subject - well, I was just having a cat-nap when a door blew shut in the wind and set off an explosion of bright white zig-zag lines in my inner eye...