In a basic sense, they show us that as a social animal we need to be around our fellow humans in order to develop a sense of culture and humanity, as well, as, in some cases, the ability to communicate as a human at all. Children do NOT need parents, they need a model to reference and strive towards, be that parents, or attained via simple interactions with a large group of their fellow species. The was an animal reserve park in Africa a while back that had a group of young male elephants delivered to them, but lacked any older males. After a period of seemingly random rhino deaths (via extreme trauma) somebody saw the culprit; young male elephants were killing rhinos out of seemingly pointless aggression. The reasoning? Elephants are, much like humans, a highly social creature, and, as this event gave evidense to, they need to be taught the rules of their "culture". Male elephants go into a stage called musk. This happens cyclically and is comparable to estrus in a female. While in musk male elephants experience a spike in testosterone, and thusly aggressive behavior. Without older males to beat them down when they are aggressive there is nothing to stop these younger males from loosing their temper, as it were, and subsequently killing rhinos. How does this relate? Simple, humans need to be taught the rules of their cultures. Everything from what you eat to how you're supposed to think needs to be imparted by older humans, otherwise you'll never really develop a sense of humanity at all. So, parents aren't needed, just a model of reference. Parents are simply the most common, however children in orphanages lack parents, and are raised (or where, at least) by multiple authority figures. They turned out more or less intact.