Well nature/nurture - I believe it's all learned but it's
learned so early in a fashion that's not controllable by
school/religion or parents really.
The input that's shaped by one's own temperament = one's
outlook.
But the input has been shaped by all past inputs - so for us to
discover "is it natural?", well, we can't.
The very questions we ASK are shaped by our culture and since
we're raised within the very culture that we're trying to pick
apart, any chance of objectivity is extraordinarily hampered.