Why are people klutzy?

I looked this up and was hoping for some scientific answer, but I got these Google results instead:

• Google Answers: Self-defense for lazy, klutzy people
• Klutzy? Take Taiji or Ballroom Dancing!
• Newsvine: Life as a Klutzy, Unlucky Man
• Skinny, klutzy kids have always dreaded the senior prom
• "Lazy! Messy! Stupid! Klutzy baby!"
• Amazon.com: "The Klutzy Parent's Guide to Coaching U-6 Soccer"

Ah, maybe this will be what I'm looking for:

Fox News: Just Clumsy or Serious Medical Problem?

Mmm...not quite interesting enough for my attention span. I was hoping for a quick and dramatic diagnosis so the next time my bottle of Amstel Light missed the edge of the bar I could say "Don't laugh, I have an enlarged cerebellum."