Good question. I know some kids that it's a chore just to make up their minds.
A clean room and all that encompasses that, to me, is a responsibility. Then again , so is caring for the animals.
At their ages, Cody(10) and Seth(8), should be responsible for their room, dirty clothes in the hamper, dirty dishes in the sink,and their dogs. Any thing above that, mowing the yard,dumping the trash,etc. should be not so frequent.Especially the yard mowing part.Age does not necessarily denote maturity( I should know,lol.)