Why do you think Rex punished Jeannette the way he did. Did the physical violence surprise you? What do you think of Jeannette’s reaction?

Rex was simply an abusive parent: he had mental health issues. Whatever justification he had for his abuse was merely a pathetic excuse to harm his own children. Jeannette loved her father because Rex and family was all she knew. I think in the end she understood how mentally ill her father was. This understanding doesn't excuse his behavior, it merely provides context for her.