when my younger brother was 3 or 4, he had grasped the concept that he came from "mommy's tummy," but developed a strong fear that he might have to go back in her tummy someday. he expressed his concern about this and felt he was too big to go back in, so he hoped this wasn't required.
A childhood belief about getting pregnant

others believed things like this
- I told my son that he used to be in my tummy when he was 4. So he asked me," Mommy why did you swollow me?"
— Christopher's mom - I used to believe that if I slept on my tummy my boobs would never grow so I never slept on my tummy.— LoLo
- I used to believe my thoughts came from my tummy.— lollypop
- I used to believe that when you fart, your tummy was breathing!— Nicholas Orsmond
- That bitng my nails would cause worms in my tummyAnon
- if you eat a seed, the plant will grow in your tummyAnon