I don't have any studies on hand, but I specifically remember a lecture I attended where it was noted that infants do not have specialized circuitry to process

I don't have any studies on hand, but I specifically remember a lecture I attended where it was noted that infants do not have specialized circuitry to process faces. Their affinity for their caretakers, at least at a very early age, is actually not a result of recognizing people, but of the caretakers subconsciously learning how to better provoke an affectionate response. You also saw this effect with the emotional robot Kismet at MIT. Its reactions were totally hardwired, but it managed to fool people into believing that it "liked" them.