When I was around 5, I used to think age was based only on the month and day of your birthday. Therefore if your birthday was July 6th, then anyone born after that day July 7 - December 31 obviously had to be younger than you.
A childhood belief about getting older

others believed things like this
- Since I was born on the 4th of July, I really thought the entire country celebrated my birthday.— -Stoddard
- My parents have the same birthday -- month, day, and year. I though all mom's and dad's had the same birthday.— Cait
- My cousic used to think he was older than me because his birthday was in June and mine was in December.— //**...Ethan...**\\
- I used to think that fireflies only came out for the 4th of July. :-)— Whitney
- Up until I was almost 11, I thought that a birthday suit was a special outfit you wore only on your birthdayAnon
- I used to think that a birthday suit was a special outfit you wear on your birthday— Bri