My 12 year old son just doesn't "get" his 9 year old sister. Last night they had a big argument (something over nothing as usual) and this morning I found a list written in his room why he hates his sister. They are just silly, childish reasons like she has no friends, she's selfish, she's always moaning etc.
Do I pretend that I haven't seen this or do I leave it on his bed so he knows I've seen it? Is it worth starting another argument?
It has really upset me to think that he can be like this because to everyone else he is a really polite boy.