I used to be convinced that, because my brother and I both have our birthday in August, all siblings were born in the same month.
A childhood belief about birthdays

others believed things like this
- My parents have the same birthday -- month, day, and year. I though all mom's and dad's had the same birthday.— Cait
- When my dad was little his older siblings convinced him that there were flocks of flying turtles.— Anonymous
- I used to believe because I was born I Abe Lincoln's birthday I had a better shot at being President.— END
- I thought I was such a lucky and special kid, because I was born on the exact same day as my birthday.— ricolarno
- My friend thought it was SO WIERD that he was born on his birthday when I told him he was.Anon
- Since I was born on the 4th of July, I really thought the entire country celebrated my birthday.— -Stoddard