Brain compartments
Each one of us has a brain compartment that is for different things. For example with boys, it could be filled with video games, food, sports, and so on. We don’t mean to stereotype gender roles here but that is usually the case. But for the eldest daughter, it would appear that things are organized much differently.
According to this post, they have sections like personal, mother, father, and sibling trauma that they have to deal with. We didn’t know that they were being hurt by all these people mentally. They always seem like they are in full control, we guess it was just a front they were putting up.