History, art and certain forms of music. When I was little my parents used to take me around old excavation sites, art museums, opera... and it was so BORING. Oh it's a painting hanging on the wall. Oh, it's a lump of rock with other lumps of rock. Oh, it's some fat guy bellowing in a hall. There wasn't any explanation of anything, you were just supposed to stare at it and magically absorb culture I suppose. I couldn't even hear distinguishable words in opera, it was just this uncomfortably big sound.
But when I was an adult I read a few history book of my own free will and found that the books weren't boring, and I learned some stuff about the theory of art and music, and that wasn't boring either. And suddenly those sorts of things were interesting because I could guess at the minds that might be behind them and interpret what they meant to me. And hey, it was an entire language (a fuzzy, general, oft-abused language, but language all the same) of feelings.
I'd never have guessed that as little seven year old me stuck reading in the middle of an art exhibition, waiting for my parents to finish so we could leave.