When I was little I used to believe that There were Three ways to have sex. Fully clothed, partially clothed and completly naked...
Only certain people could have sex one of the ways but no other way and that the first time you attempted to have sex you would figure out which way you were.
I also believed that if you had sex differently than another person, you couldnt have sex with that particular person....
A childhood belief about sex

others believed things like this
- Until about the age of 13 i used to think that oral sex was 'normal sex' but fully clothed!!— Daveyd
- I used to think that sex happened on accident while clothed.Anon
- I used to beleive that sex was sitting clothed or unclothed making out.Anon
- i used to believe that when a person moved away, they switched houses with the person that bought their house— alli
- I used to think that if a white person and a black person has a baby it would be mexican.— J
- I used to believe that anonymous was a person, and I thought, "Gee, this person writes a LOT of poems!"— Katie Albano