Alternative Character Interpretation: There is plenty of debate over if Rhoda's sociopathy is really a "bad seed" or a product of her upbringing which is even a debate between characters in the book itself. Given her grandmother had a history of crime and she was raised in a rather upperclass home, one might tend to make her as a "bad seed". There is a position that turns criminality into a classist concept where bad people are raised in bad environments. Rhoda proves this theory wrong and thus is considered to be a bad seed via her genetics. Although the less spoken out loud idea is to Take a Third Option in that Rhoda is a completely normal occurrence. It is instead the society that doesn't want to admit this and prefers to pretend it is either a genetic failure or a nurturing failure. Which may just be some depressing Truth in Television as people who kill others like Rhoda have been with us forever and society hasn't really found any way to stop it.
The classist view that psychopathic criminals are the result of poor upbringing and poverty (which the adults discuss at length in the book) was extremely popular in psychology/criminology circles of the period, when modern theories of psychology were only beginning to seep into mainstream consciousness. Author William March—who himself grew up in poverty in rural Alabama with an alcoholic father, suffered psychological problems, and witnessed psychological devastation among his fellow soldiers during his service in WWI—had a more cynical view of the popular belief and created the character of Rhoda based on the idea of a congenital psychopath born into an exemplary family with no history of neglect, abuse, or deprivation. The whole story can almost be seen as March's Take That! to this theory.
Complete Monster: Bessie Denker, born Schober, was a sociopathic murderer who systematically killed her own wealthy family members to her profit. Dispatching her younger siblings as a child, Bessie soon after took the lives of her grandfather and both parents. Marrying a wealthy man to enrich herself by convincing him to take out an insurance policy, Bessie then killed him as well, careful to keep up the façade of a sweet, caring community member to avoid suspicion. Later marrying the father of heroine Christine, Bessie killed him too, before being finally exposed by her cousin, killing said cousin and three of her own children—Christine herself barely escaping her wicked mother—hoping to frame her dead cousin and escape justice until being caught and executed. Even long after her death, Bessie's memory haunts Christine well into adulthood and her genes give way to Christine's own daughter Rhoda taking up her grandmother's mantle as a budding psychopath in her own right.
The Woobie: Christine, and especially Mrs. Daigle, who only has vague suspicions about what really happened to her son that no one takes seriously.
