A central question permeating the narrative is whether Kevin's violent tendencies were innate or shaped by his upbringing. Eva reflects on her own ambivalence towards motherhood and her struggles to connect with Kevin, questioning if her own shortcomings contributed to his disturbing path. Shriver doesn't offer easy answers, instead compelling us to consider the complex interplay of genetics and environment in shaping a child's development.

Eva's narrative is saturated with guilt and self-recrimination. She grapples with the knowledge of her son's actions and the possibility that she could have prevented the tragedy. This theme extends beyond the immediate family, prompting reflection on the role of society, institutions, and mental health awareness in preventing such acts of violence.

Eva chooses letters as her medium to confront her trauma and communicate with her estranged husband. This epistolary format highlights both the power and the limitations of communication. While Eva finds a degree of catharsis in expressing her feelings, the letters also underscore the gulf that exists between her and her husband, mirroring the fractured communication that characterized her relationship with Kevin.