I used to believe that siblings had to marry only siblings in the other family. For example, my husband's brother could only marry my sister, and so on. I tried asking my parents what would happen if someone with 2 sisters married someone with 1 brother, but they didn't understand what I was talking about.
A childhood belief about marriage

others believed things like this
- I used to believe you had to marry your siblings when you grew up.— Cade Whitbourn
- That you had to marry your sibling. During this period of time I devoliped a crush on my brother.— don't worry I'm a girl
- i used to think that every family had a brother and sister and they married eachother when they got olderAnon
- I used to think I was going to marry my mom, even though my dad was already married to her.— nick
- I totally believed my siblings when they told me the family was aliens and had a space ship in the garage.— cully
- I Used To Believe That You Can Marry Your Sister Or Cousin As Optional!— KellGirl