I would like to point out that the number of things that make up the human being are innumerable. Genetics, psychology, feelings, environment....it would be impossible to say 'some people are born evil and some or born good' and NOT be correct. Likewise, the number of things that contribute to a breakdown in the appearance of sanity are just as innumerable, and it would also be correct to say some people are made insane.
The truth is, society itself defines good and evil, sanity and insanity to the best of its ability. These generalized groups of judgments exist so that a society can continue to function effectively. The collective insanity of humans, however, is most obviously evidenced by our inability to patiently learn to understand one another. No one thing had contributed to more horror, pain, cruelty, destruction and generalized torment than our unwillingness or incapability to communicate effectively with each other.