I arrived at my sister's house while she was at the grocery store. My 15 year old nephew showed me the metal "sword" that his visiting friend had made for him. The friend had one, too, and after I expressed my admiration and turned to my iTouch to check email, the two began dueling. In the living room.
"Has your mother talked to you about this behavior?" I asked.
"Good point," he said.
And experts say 15 year olds can be left home alone.