Studies have been done with infants showing that they are developing a sense of, for instance, fairness at an age of just a few months. The suggestion is that, as butchersapron alluded to, we're born with a predisposition to look for something like 'right' and 'wrong' in a very similar way to how we are born with a predisposition to look for something like language, and that we're very active in our acquisition of these things.
To what extent the content of what is right or wrong is then culturally determined is a separate point, no? If we really do have a more or less innate sense of fairness, one that we don't learn from others, there may be limits to what we will accept as fair, and if we're born with a predisposition to look for binaries (right/wrong, good/bad), that will have an influence too, but it seems pretty clear to me that, just as we can learn any language, whatever framework we're born with contains enormous room for post-natal development. That extreme flexibility is a very important part of what humans are.
