A man can be made to say or do anything, with enough conditioning; we are animals after all. I'm not arguing the irrelevance of context here, but I am saying that people have natural tendencies which amount to an implicit innate moral compass. People want to be good and chill.

Most people want to be nice to their neighbors / tribe.

Most people find violence disturbing.

That they live in circumstance that encourages, requires, them to kill, to manipulate, to be an asshole - is just circumstance. That's why being a Good Person is Hard. You need to remain true to yourself, and fight against all kinds of external forces that seek to corrupt you.