Are villains born or made? This simple question has sparked ongoing disputes over the years, delving deep into studies of criminology and behavioural psychology.

As someone who is interested in true crime, I often wonder whether psychology plays a role behind the scenes of some of the world’s most atrocious murders. From relationships turned sour to business disagreements that took violent turns — was it fate predetermined by genetics, or was it the result of a series of unfortunate events that shaped a cold-hearted soul?

To dig deeper, I turned to these studies: American psychologist Philip Zimbardo’s 1971 Stanford Prison Experiment and Danish criminologist Karl Christiansen’s 1977 twin studies.

In the Stanford Prison Experiment, Zimbardo recruited 24 ordinary, law-abiding college men. They were split randomly into two groups — ‘Prisoners’ or ‘Guards’, in a simulated prison environment designed with input from a former inmate. The study was meant to test how much behaviour comes from personality versus situation.

What happened was shocking. Guards quickly became cruel, humiliating prisoners and treating them “like animals.” Prisoners, meanwhile, forgot they could quit at any time. They begged for release, then obeyed again when denied. Even Zimbardo himself slipped into the role of ‘Prison Superintendent,’ prioritising control over ethics.

Aggression emerged only in the artificial prison environment, shaped by its power hierarchy. I believe all participants, including Zimbardo, blurred the line between reality and roleplay, consumed by their assigned identities, which is free from genetic influence.