I say this all the time, but it never ceases to fascinate me that we all listen to the same thing and yet hear something completely different. Had I been born into money I reckon I'd have probably tried to become a researcher into the relative roles of nature and nurture on musical preferences.
At the risk of sounding like a nutter, some of the experiments they've done with mice are really interesting, reversing stress induced depression (yes a mouse can have depression but not sure how ethical it is inducing it) through the playing of music at night; how mice react differently to metal compared to other genres etc. in humans there's all sorts of stuff, sound perception differences of left and right handers etc.