Monkeys is lovingly titled after the affectionate nickname the mother gives to the children, her little monkeys. That's a pretty good place to start when analyzing the book, because it indicates that really, the story is about the psychology of the children, not the adults. We see more of the mother than of the father in the story, so it might seem like the story is about the mother, but it's not. It's about the little monkeys.
The kids understand that their father literally hates their mother with guile and disgust, and the fact that such a family situation is not conducive to children's psychological development. The story places this knowledge in the foreground, because it would have been that way to the children too. Children are sensitive, especially to negativity, and by raising children in a home that was not full of love but hatred, the children are wrongly wired by their upbringing, and most of them struggle with drug abuse and suicidal depression.
It's no surprise that abusing children damages their psychology, but as the book explains, it doesn't even have to be abuse against any one child in particular—the children are damaged enough just by living in their atmosphere of constant tension, hatred, regret and resent.
When the family finally comes together at the end of the novel, it's an important reminder that there was love underneath all the sadness and abuse. When they stand together, they are living in the possibility of a brighter future. It's important to notice that although the mother in the novel commits suicide, the family lives on. The father remarries and the children go their own way. There is tragedy in this story, no doubt, but it's a reminder to watch out for mental illnesses and to get them treated seriously by a professional, because untreated, mental illness or emotional imbalance can cause great harm to one's self and to their loved ones.
