The documented first year of four babies in four different corners of the world:
Update: This NYT Magazine story on the moral life of babies is a great complementary reading to the movie:
The mental life of young humans not only is an interesting topic in its own right; it also raises — and can help answer — fundamental questions of philosophy and psychology, including how biological evolution and cultural experience conspire to shape human nature. From Sigmund Freud to Jean Piaget to Lawrence Kohlberg, psychologists have long argued that we begin life as amoral animals. One important task of society, particularly of parents, is to turn babies into civilized beings — social creatures who can experience empathy, guilt and shame; who can override selfish impulses in the name of higher principles; and who will respond with outrage to unfairness and injustice.
A growing body of evidence, though, suggests that humans do have a rudimentary moral sense from the very start of life. With the help of well-designed experiments, you can see glimmers of moral thought, moral judgment and moral feeling even in the first year of life. Some sense of good and evil seems to be bred in the bone. Which is not to say that parents are wrong to concern themselves with moral development or that their interactions with their children are a waste of time. Socialization is critically important. But this is not because babies and young children lack a sense of right and wrong; it’s because the sense of right and wrong that they naturally possess diverges in important ways from what we adults would want it to be.