When I was very young (3 or 4 I think), I was led to believe by my Dad that my last name was from an ancient indian word. I held this belief until I was around 9 or 10 and shared this information with some of my friend. They laughed so hard they cried. I said "come with me" and took them to see my dad. After telling my dad about it, he started busting out laughing as well. Apparently he was joking with me and never thought that I'd retain that information. I was humiliated, but luckily I had good friends that didn't give me too hard of a time about it. :)
I think that incident is the root of my cynical nature. ;)
A childhood belief about names

others believed things like this
- i used to believe that my dog was really a cat in disguise trying to get information on the dog empire!— strange and used to be stupid
- When I was a young boy I thought when we cried or when we laughed we won or we lost one minute of our life. — loulou83
- When I was very young, I thought that God was married to Mother Nature, and that together they made weather.Anon
- I also thought that people in different countries coughed, sneezed, laughed, or cried in their own language!— Mini
- When I was young, I heard the word 'minion' for the first time and thought it was a miniature onion.— Karin
- i used to believe that root beer was made with root juice and beer— tm