Apparantly I always used to breathe through my mouth up the age of 7.
And then I had a tonsilectomy and I now always breathe through my nose, lest I physically can't or if there's a nasty stink around. :s
Coincidentally, I haven't snored in my sleep since I had my tonsilectomy.
I'm not sure if that's supposed to be a byproduct of the surgery, or that's just me.