How old are children when they first make the distinction between moral, conventional, and personal domain?

Children as young as 2 or 3 begin to make these distinctions (Hamlin & Wynn, 2011; Nucci, 2009; Thompson, 2012). Children understand, for example, that it's wrong to hit and hurt someone regardless of where you are and whether or not rules prohibiting it exist. Some researchers even suggest that we are born with a rudimentary sense of justice that can be observed in the first months of life (Bloom, 2010).