Just wood and fiberglass. Excluding all the photos, jewelry, paintings and furniture that cannot be replaced, important papers (they are doctors), computers, cars, and everyhing else they own.
Well I've never concerned myself over material possessions. Cars / Ipods / Computers are all temporary things that eventually break.
Everything but photos in that list can be re-bought, after all, your grandparents are rich right? Not to mention, I have all my family photo's stored online, and any official documentation should be stored online too.
So yeah, if my house burned down, I'd be joking about it in the apartment.
Would you be A-OK with it if I burned down your house?
Well that's arson, Zalot.