My older sister got me into a lot of the music I like. I used to automatically dislike anything she liked, as that's just the way things went when I was a kid, but now I'm older I'm finding a lot of things I used to hear her listening to are now the things I like too.
Then there's music TV. I'm a sucker for music videos, so I'll often have them playing in the background and something will occassionally catch my attention and make me think I must get the track <3