What are the Three Big Questions You have at this Time?

After just beginning to read "A Child Called It," a nonfiction book written by Dave Pelzer, I have major questions about what motives are behind a mother physically abusing her own son. The first chapter describes, in detail, what life was like when their family was happy and prospering in the California area. My first question would have to be what major event happened that made the dynamic of the household so bitter for one child, when the mother used to care so much? Next, it is shown that the youngest of the three sons was the only one that got abused and treated so harshly. Why would the mother only single out one for being a 'bad boy' and the brothers not try to help the situation? Finally, the mother preformed many acts of punishments that are cruel and unusual. She forces Dave to live without food and complete specific chores in an amount of time. How would someone be able to come up with these ideas to hurt another person, one that they even gave birth to? I hope that by reading further and becoming more invested in the book, I will figure out the answers.