I used to believe that there were whole other worlds on the insides of mirrors and that when I looked into them, I was just catching a glimpse of another universe. The girl in the mirror and I just happened to look at each other at the exact same time and wear the same clothing, but our lives were otherwise fairly different.
The flip side to this were reflections in glass. Especially at night, I always thought I'd be able to see ghosts in them if I just looked long enough.
A childhood belief about mirrors

others believed things like this
- I believed that if I looked too long in the mirror admiring myself the Devil would appear.— Paul Elletson
- I'm scared of mirrors because I think that there are ghosts in mirrors— est
- I used to believe that there was a person in the mirror who looked exactly like meAnon
- I used to think that if I looked in a mirror for over 5 mins I would dissapere to Narnia!— Quako
- when i was a little girl i thought God looked like my grandma and dressed like the statue of liberty. Anon
- I used to think the lyrics to "Too Legit To Quit" were "Do the flip, do the tootsie flip"— cassie