This is a powerful book about good and evil. Steinbeck raises the possibility that good or evil traits can be inherited. Cal, with seeming evil proclivities, possibly inherited from his clearly evil mother, wants to be good... tries to be good... and lives with this internal struggle. Cal's brother Aron is a good boy... but, unlike risk taker and high achiever Cal, he lives his life fearing failure. One of the strengths of the novel is how well Steinbeck writes about these moral complexities.