My stepdaughter, who lives with her dad & me full time but stays with her mum a couple of nights per week, has tantrums/screaming/shouting/answering back/flouncing/stomping episodes on an almost daily basis - mostly in response to not getting her own way (eg, told she can't watch telly), being asked not to do something (such as not answer back) or being told she must do something (like cleaning her teeth or going to bed). She is going through puberty and started her periods about a year ago, but her bad behaviour is constant, not just pre menstrual, and almost every interaction we have with her turns into a battle. It does not seem to matter whether it is a day when she is being given a treat or something nice or a time when she has got into trouble she still behaves in an extremely bratlike way on a daily basis.
Is this normal? Or should we be investigating to see if there is a problem?