Hello
My name is doctor Humicobob,
my job is to deal with familys like your self and help them with there problems. I have seen many situation like this. Familys come to me and don't like what they here, so they never come back. A few years later I here back from them that they were trying to indure girlfriends or close friends, teachers and other family members. Once I came across an insident were a family was so frustrated with there 16 year old daugter that the other siblings had to move in with other family members as it was not safe anymore. These are common symotoms of not normal behavior. I'd get help right away or you might be dangoring your self.
It does sound as if he has learned this behavior,I agree that you could use some professional help .
I'd see a children's therapist with him, just to ask for advice. Maybe this all stems from being frustrated or hurt at the cousins' house, or maybe something else is involved, but it would be a good idea to get a professional opinion if you are concerned. Sometimes a mother's intuition is right on, and if yours is saying this is not the normal behavior, I would at least check things out.