It is impossible to be "good." For the sake of this post, to be "good" is to be of favorable character, which is achieved through actions that are considered above and beyond what is acceptable. To be good, you have to do good things, but these good deeds are only considered "good" because society says they are. So, what happens when a "good person" is put in a society with opposing values? Is he then considered evil? See, the only thing humans value is their own lives; genocide is horrible when they are committed against creatures that they find favorable, but it is "the right thing to do" when it is committed against creatures they find vulgar or threatening. We are only as good as society allows us to be. In the words of Franz Boas himself, "civilization is not something absolute, but ... is relative, and ... our ideas and conceptions are true only so far as our civilization goes."