It's okay. Don't worry about it.
What impact does that have on how you present them with setting?
I use cartoons.
For my Earth Zero supers game: a fucking (chemically enhanced) marathon of
Avengers Earth's Mightiest Heroes, Followed by, "Kind of like that, mashed with Hellboy comics, and old Jack Kirby stuff," and we were off.
The Metal Earth is actually kind of easier because there has been some independent interest and they've both read stuff and asked a lot of questions. Really, though, that is a first and I'm not sure what got them going.
Also, I do a lot of (rushed and half assed) drawings of stuff, which i introduce during the course of play. I almost wish I'd never stated on that though, because although they really appreciate it, they also expect it and are disappointed when I don't come through (I'm working on some drawings for Monday's ICONS game between posts tonight).