1. Biological theories
1.1. Neurobiological theory
1.1.1. Gacy’s childhood environment (abusive/chaotic) lacked the necessary conditions for fostering cognitive, behavioral, and interpersonal skills
1.1.1.1. contributed to deficiencies in emotion regulation, impulse control, and empathy
1.1.1.2. possibly attributed to toxic relationship with his father
1.1.2. Brain structure/imbalences are often a cause of deviant behavior, but Gacy’s brain was found to be normally structured in a post-mortem exam
1.1.3. Because Gacy's father was violent and abusive, Gacy could have a genetic predisposition to violence
1.1.4. https://www.sciencedirect.com/science/article/abs/pii/S0047235217305299
1.2. Biological explanations of criminal behavior theory
1.2.1. Gacy exhibited manipulative behavior and lacked empathy which could be attributed to impaired autonomic functioning
1.2.2. if Gacy had functional abnormalities in his brain, that could explain his lack of impulse control and moral reasoning which contributed to his inability to stop his violent urges and understand the consequences of his actions.
1.2.3. Abuse suffered in his childhood could have triggered violent traits that Gacy was genetically predisposed to
1.2.4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6640871/#R85Psychophysiology
1.3. Two-Path Theory
1.3.1. Gacy was an offender for most of his life (late adolecence/early adulthood to end of life)
1.3.2. slightly different from normal life course offender since he was closer to adult age when he started offending
1.3.3. exhibited similar traits to life course offenders, just exhibited deviant behavior later on in life rather than earlier
1.3.4. https://soztheo.de/theories-of-crime/biological-theories-of-crime/two-path-theory-moffitt/?lang=en Life-course persistent offender
1.4. Epigenetics theory
1.4.1. Gacy's childhood experiences of abuse and neglect align from his father may have contributed to violent behavior later in life
1.4.2. Gacy exhibits the theories idea that violent criminals often come from environments with abusive or absent fathers
1.4.3. Due to an abusive environment and health issues, Gacy could have developed his violent traits as a result of DNA changes brought about by epigenetic changes
1.4.4. https://www.dw.com/en/unlocking-violent-crime-through-epigenetics/a-45964140
1.5. Traumatic brain injury (TBI) theory
1.5.1. Gacy experienced several head injuries during his childhood, including a traumatic incident where he was struck on the head by a swing
1.5.1.1. Created a blod clot which cause him to blackout randomly for several years before being treated
1.5.2. Gacy exhibited traits such as impulsivity, poor social judgment, and aggression, which align with TBI
1.5.3. There is a higher risk for individuals with a history of TBI of engaging in violent or criminal behavior, as observed in Gacy's case
1.5.4. https://doi.org/10.1016/S2215-0366(18)30062-2
2. Psychological theories
2.1. Attachment theory
2.1.1. Gacy's troubled relationship with his father and early experiences of abuse may have influenced his attachment style and emotional development
2.1.2. lack of a secure attachment bond during infancy/childhood could have contributed to difficulties in forming healthy relationships
2.1.2.1. Gacy did not have a good relationship with his father, and he had two failed marriges (lack of healthy relationships)
2.1.3. Gacy's inability to seek comfort and security from others during times of stress may reflect disruptions in his attachment behavioral system due to an abusive environment
2.1.4. https://www.simplypsychology.org/attachment.html
2.2. Offending behavior theory
2.2.1. Gacy experienced traumatic events during his childhood, including an abusive father and a head injury, which may have contributed to psychological issues later in life
2.2.2. Gacy's criminal behavior, particularly his sexual assaults and murders, could be understood as a maladaptive coping mechanism resulting from unresolved trauma
2.2.3. Gacy's pattern of behavior aligned with victims becoming perpetrators as he may have been projecting the abuse he experienced onto others.
2.2.4. https://doi.org/10.3402/ejpt.v3i0.18968
2.3. Psychodynamic crime theory
2.3.1. Gacy's troubled relationship with his abusive father and desire for approval could have impacted the development of his superego
2.3.2. His antisocial behavior, including his sexual assaults and murders, could be seen as attempts to gratify his id
2.3.2.1. Via, seeking immediate pleasure without regard for societal norms or consequences
2.3.3. Early childhood experiences of abuse/trauma could have contributed to the formation of Gacy's personality traits
2.3.4. https://www.tutor2u.net/psychology/topics/psychodynamic-explanations-offending-behaviour
2.4. Psychopathy theory
2.4.1. Gacy displayed shallow emotional responses and lack of empathy, traits consistent with psychopathy
2.4.2. His criminal behavior, involving manipulation and deception, which aligns with the interpersonal tactics of typical of psychopaths
2.4.3. Gacy's actions could be attributed to high functioning psychopathy, characterized by emotional deficits and premeditated acts of violence
2.4.4. https://doi.org/10.3233/RNN-139001
2.5. Sexual deviance theory
2.5.1. Gacy's actions, which included exhibitionism and sadistic behavior, align with the behaviors categorized as sexually deviant
2.5.2. His homosexual tendencies would have been considered sexually deviant during that time period
2.5.3. Gacy also exhibited pedophilia and necrophilia which are sexual deviant behaviors
2.5.4. https://www.sciencedirect.com/science/article/pii/S0191886914003419
3. Sociological theories
3.1. Social control theory
3.1.1. Gacy's early life involved strained relationships with his abusive father which may have weakened his attachment to society's norms
3.1.2. His feelings of rejection and desire for approval (from his father) could have also contributed to a weakened bond
3.1.3. Gacy's actions may reflect a disregard for the consequences of his behavior, indicative of weakened social bonds
3.1.4. https://www.simplypsychology.org/social-control-theory.html
3.2. Labeling Theory
3.2.1. Gacy's actions, particularly his crimes against young men, were perceived as deviant and criminal by society
3.2.2. Gacy's internalization of his deviant label may have reinforced his criminal behavior and self-perception as an outsider
3.2.3. The negative reactions of others to Gacy's behavior and societal given labels played a role in shaping his identity and actions
3.2.4. https://www.britannica.com/topic/labeling-theory
3.3. Routine Activities Theory
3.3.1. Gacy targeted vulnerable individuals like teenage runaways and male prostitutes (suitable targets)
3.3.2. Gacy had access to his victims through his employment as a clown, construction company, and his other social connections (opportunity)
3.3.3. https://simplypsychology.org/routine-activities-theory.html
3.4. Social learning Theory
3.4.1. Gacy may have learned his deviant behaviors, including violence and aggression, by observing others
3.4.2. Children will imitate behaviors they observe, and Gacy was exposed to an abusive father at a young age
3.4.3. Gacy's mental states, such as his motivations and desires for control, could have influenced his learning and adoption of violent behaviors
3.4.4. https://www.verywellmind.com/social-learning-theory-2795074
3.5. General strain theory
3.5.1. Gacy's relationship with his father and desire for approval could have led to a negative mental state and pressure for corrective actions
3.5.2. Gacy experienced strain and stress in his life due to societal expectations/pressures and his own personal struggles
3.5.3. Gacy's failure to meet expectations of success, coupled with feelings of inadequacy/frustration, may have contributed to his turn towards deviant behavior
3.5.4. https://faculty.wcu.edu/studentanthology/writing-across-western/criminology-and-criminal-justice/47-2/