When "Rugrats" was new I used to believe the voice actresses, especially E.G. Daily for some reason, were actual babies. Imagine my surprise when I learned they were women in their 30's. Now I a big fan of Ms. Daily.
A childhood belief about cartoons

others believed things like this
- I used to have to say the Lord's prayer everyday, but I would wonder where my daily bread was.— caledonia
- I used to believe that peanuts were a daily must to strengthen the memory like elephants — Qb Cheese
- That by drinking a daily dose of buttermilk one would clean the blood thereby avoiding ACNE— Richard in Durham
- I thought the women in Prisoner Cell Block H were actresses banged up in prison themselves.— Reb Kean
- I thought baby back ribs were from actual babiesAnon
- For some reason, I used to believe that women only got raped on train tracks.
— Jessica Tinch