When I was four years old, I used to believe that the previous sister or brother can choose the gender of next child in family.
My mum allaways asks:
"A brother or a sister, which do you prefer? "
My sister said she wants a girl and I borned.
I said I want a boy and my brother borned.
So I used to believe this theory very much.
A childhood belief about sex

others believed things like this
- I used to think that Cain and Able were brother and sister (with Able being the girl).— Duh
- i used to think that every family had a brother and sister and they married eachother when they got olderAnon
- I used to believe my parents were brother and sister, and that everybody's parents were brother and sister.— Rachael
- I used to belive that my mum and dad lived together cause they were brother and sister— Corin
- I used to believed that the children borned by tucking the finger info nunptial rings!!!— Silvia Mazzei
- First I believed that my parents were brother and sister. Then I thought that my dad was also my mums dad. — Rainbow