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1/3 of Men and 15% of Women frequently fantasize about killing someone they don't like; 3/4's of Men and 60% of Women occasionally think of doing so.
Statistics cited by Steven Pinker [born 1954], Professor of Psychology at Harvard, who argues that the human mind, like the human body, has been designed by natural selection through the process of biological evolution. A brief interview with Pinker discussing his book The Blank Slate here.