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In 2005, while studying PET scans of murderers alongside scans of his own family, which he was using as normal controls for an Alzheimer's study, James Fallon found that one control scan showed the low orbitofrontal and anterior temporal activity he associated with psychopathic killers. When he unblinded it, the scan was his own. Yet he had never been violent or criminal, which made him a living test case for biological determinism.
Fallon argues that a violent psychopath needs three factors together: (1) low function in the orbital and ventromedial prefrontal and anterior temporal cortex, (2) high-risk gene variants such as low-activity MAOA, and (3) abuse or trauma in early childhood, especially around puberty. Any one or two of these factors alone does not produce a killer. In his own case, a loving and protected childhood kept the third leg missing.
A person can have the core psychopathic traits of shallow empathy, manipulativeness, risk-seeking, and charm with little guilt while staying functional and even successful. Such a person channels those traits into competitiveness, social dominance, and low-level deception rather than violence. Fallon uses this label for himself: his family and friends confirmed he was charming but emotionally cold, and indifferent to hurting people close to him.
Fallon claims that after he accepted the diagnosis, he began consciously acting as if he cared, as a kind of game, doing what a decent person would do even though he did not feel it. He says the outward behavior changed and the people around him noticed. His argument is that biology loads the dice but self-knowledge and choice can still shape conduct, even without changing the underlying feeling.