This theme is woven throughout Keep It in the Family as all of the primary characters deceive themselves and others in various ways. For example, although Debbie reviles her parents for their compulsion to abuse and murder children and hates them for intentionally harming her and her brother George, she eventually embarks on her own systematic murder spree and willfully deludes herself into believing that she is somehow different from her parents. Debbie justifies her behavior by telling herself that, whereas her parents craved violence, she has a benevolent compulsion to save children by removing them from an uncaring world. Debbie also has a pattern of manipulating others and justifying her behavior by claiming that she makes hard decisions to protect herself and her family. These attempts at rationalization merely obscure the fact that her actions are purely selfish. Even when she manipulates Finn and Mia into believing that Sonny is dead, she defends her behavior by insisting that her actions are necessary.

While Debbie’s twisted psychology stands as the most prominent example of self-deception, Finn runs a close second, for he actively follows in his mother’s murderous footsteps, and in the meantime, he manipulates his loved ones and deceives himself.