What is the psychological aspect of the novel The Alienist?

As the reader makes their way through this novel, they soon come to realize that many of Dr. Kreizler's beliefs are the basis for modern psychology. Kreizler looks to a person's childhood to see what made them the adult they have become and how that childhood causes a person to act in a specific way. This is very much like modern psychology in that many psychologists look to a criminals childhood to guess as to how a criminal will act and respond to specific events or actions. For this reason, changing times is a theme of the novel.