Children between three and five years develop an understanding that they are potentially liable and that they are building a history of transactions with others. Needless to say, parents and educators foster this development in all cultures, but this fostering is essentially the enforcement of the basic rules of reciprocity, the constitutive elements of human exchanges. Children are channeled to adapt to these rules they depend on to maintain proximity with others. From this, they begin to build a moral space in relation to others, a moral space that is essentially based on the basic rules of reciprocity.
Again: Rochat, P., 2009. Others in Mind: Social Origins of Self-Consciousness. New York: Cambridge University Press, p. 180.