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Within every human there is a capacity for great destruction, to oneself and other individuals, which can be manifested physically in the horrors you described. No-one morally is spared from blame, it just depends to which degree what we are doing hurts others.

Anyone thinking the evil potential isn't innate biologically and under a correct circumstance wouldn't surface is delusional. This is the literal Jungian shadow.

E.g. your village has been destroyed by invaders as a child, killing your father for example, decades later leading you to lead a brutal dictatorship out of anger; enforcing that anger on untold others. Everything the now old man would enforce would never bring back his father.

NB I also have this perspective.