I ran a mess of Story Games at a local convention over President's Day weekend: "Primetime Adventures", "Dirty Secrets", "With Great Power...", and "A Penny For My Thoughts". In the program book for the convention, I listed "Dirty Secrets" as "18 and over" due to the mature nature of the game. But for the others I thought playing with kids would be fine. I've run D&D games for kids (five ten-year-olds in a year-long campaign!) and I've had adults and kids at the same table of traditional RPGs at conventions without much difficulty.
Based on my experience with kids and adults at the same table for a Story Game, I'm going to list all my Story Games at "18 and over" in the future. The creativity of adults and the creativity of children did not work well together. In these type of games, everyone needs to be "on board" with the creative ideas at the table or they won't have fun. PtA in particular really needs players to veto ideas they aren't going to enjoy.
I had one PtA game where the kid at the tables wanted the show to be "anime teddy bears with machine guns". The adults at the table clearly weren't on board but they didn't want to crush the creativity of a child by vetoing her idea. But if they didn't veto the idea, they weren't going to have fun. They were put in an uncomfortable situation by the nature of the game and the nature of the group - not really anybody's fault. All four of the Story Games session I've run/played with a mixed group of adults and kids had similar problems.
So that's my advice - don't run Story Games for mixed groups of adults and children. Has anyone else had similar experiences? Contrary experiences?