Exactly. What's important to the game is who you're character is, not who he or she was. A backstory might make for an interesting read and might provide a couple of future plot-hooks. But when you start playing the game, to what extent does it really matter why your dwarf fighter is a one-eyed halfling-hater so much as your dwarf is a one-eyed halfling-hater.
(...I need to come up with better examples... )