my ds2 is 3.4 and for the past few weeks he's started blaming his brother and sisters for things hes done.nothing bad,but for example he always says that dd1(8)has pumped if he has,and earlier i asked him if he'd left the front room light on and he said'the baby did it'(she is 12m old and not even crawling yet).he smiles when hes saying these things.is this quite common for a child his age to do?