How much damage could a fallen tree inflict on a house?

My house is surrounded by really tall trees, extremely tall. Our whole backyard is wooded. My house is built on a hill, it has 2 floors seen from the front, 3 on the back, basement included. It's a basic house. It's fairly newish. We have already had a tree fall recently back there, but luckily it barely missed hitting another closer to the house, and hitting our house. My initial question is: If a tree back there were to fall, what damage could you estimate would be done? Are me and my family safe?