Is it normal for cousins to be mad at each other. It seems my daughter and her cousin are mad at each other one moment, and the next, they're best friends. I just don't get it.
If they are both girls then I would say it's a kid thing rather than being related to a family connection. Or perhaps being related gives them more security to squabble without worrying about losing the bond?
I'd say that this is pretty normal. My mother is still best friends with the woman she lived next door to fifty years ago and she says they fell out with each other every day!