I was 10 when I started playing fantasy role-playing games, thanks to a friend's older brother and Dungeons and Dragons 1st Edition. Two years later, I was gathering Advanced Dungeons books, devouring fantasy novels, developing my own worlds, and running games for my friends. Around the same time, I discovered Heroquest, which played a lot faster than D&D and was a good change of pace from more immersive story telling games.
My oldest kid is now 5 and we had a great time this summer playing a story game around the campsite with his cousins, some yahtzee dice, and a simple system I made up on the spot.
When did you first play a role-playing game and/or when would you introduce your kids, nieces, or nephews to the game?