What does the novel say about how we should treat our children, and each other?

In the context of the creature being Victor's child, the story is cautionary tale. Don't abandon your child or it will hunt you down and kill your family! Really though, the theme of parental responsibility resonates throughout the story. The creature is an intellectual and emotional baby when it is created and abandoned. Victor pays a heavy price for his revulsion in the end. Victor had a good roll model in his own father but chose not to follow his example.