Human beings are not born pure. It is instincts that make a person corrupt, not external forces, such as parenting, environment, social excuses, et cetera. For example, if a human(blank-slate) were left in the wild with nothing, no food, water, clothes, technology, or memory of civilization, what is the first thing it would do? Hunt. It would kill animals and plants to survive. Human beings are not born pure because of the internal tick that makes everything fall into the circle of life.