The one song I can credit to shaping my entire life is Pink Floyd - Another Brick In The Wall (Part 2). I can remember my parents playing this when I was a kid, and I think it's the song that's led to my love of music. Amusingly, the only other one is probably Robert Miles - Children, as this really got me into trance, which has since led me into every other genre of electronic music. That one's not too great - no kidding! - but it deserves a mention