When I was a teenager, my father brought an Ubuntu 6.06 CD home from his workplace. It didn’t interest him much, but he let me play with it on an old family computer. Once the setup finished I spent as much time as I could playing with the colour scheme, figuring out how to install Compiz for the cube animation, and making Kingdom Hearts wallpapers. Those activities were mostly playful, but they ended up helping me get exposure to tools like cd, ls, and apt-get.
Today I feel a lot more confident in using Linux (or any Unix, really), but that’s likely 100% due to having time to spend playing and being curious.
There’s a lot of discussion about an education in computing helping people get ahead economically, but part of me wonders how much proficiency comes from being a child on a Commodore 64 than learning express+mongodb in a few weeks (not that being the latter is a bad thing, either!).