Of course they do! Silly mouse! LOL!

But that is only the practical and logical conclusion.

Here in the south of England we only very rarely get snow, but all our rooftops are sloped - some of them quite steeply. I think this is a lot to do with the fashion at the time the house is built. Edwardian houses in my area, for example, are pretty 'alpine' in profile, despite the fact that there has only once ever been sufficient snow here for me to build a snowman, way back in 1974, or thereabouts, and even then I had to steal some of the snow from next door's garden!

So it would appear that in my area at least, fashion plays a role in rooftop architecture, as much as climate and practical matters.

EDIT: ninjad by Red!