I thought everyone lived to be exactly 100 and then died on their 100th birthday (if they didn't die from accident, murder etc before then) Later when I learned about life expectancy I thought everyone in that country lived to be exactly that age and then died.
A childhood belief about people

others believed things like this
- When I was little, I used to believe that everyone died on their 100th birthday.— Kristen
- I usd to believe that, all Americans were left handed and we all died when we reached our 100th birthday!— Greg Baron
- I used to believe that everyone lived until they were 100 and you dropped dead on your 100th birthday!— Natalie
- I thought there was some video games so hard that if you died on them you also died in real life!— Kakuri
- When I was little I believed when an actor died in a movie, he died in real life.— Ben
- every one lived until they were 100 and then they died no questions asked— sext4eva