I used to believe that people only grew, physically and in age, on their birthday.
A childhood belief about birthdays

others believed things like this
- I used to think you only grew on your birthday.Anon
- Up until I was almost 11, I thought that a birthday suit was a special outfit you wore only on your birthdayAnon
- I thought that people with the same birthday were always the same age.Anon
- I used to think that a birthday suit was a special outfit you wear on your birthday— Bri
- I used to believe that on your birthday, you didn't advance to your next age until you ate your birthday cake.— Casi
- My parents have the same birthday -- month, day, and year. I though all mom's and dad's had the same birthday.— Cait