I guess the idea of what makes a person "real" is subjective. If you look at the opposite of maturity, in my eyes it involves a baby that cannot care for itself. It places many burdens on the caregivers, but it also gives great joy in most cases.
So, you could say that the baby is as real as it gets, when it wants to poop, it poops, when it wants to pee, it pees. When the baby experiences intense emotions or it is hungry, it cries. When it is tired, it sleeps. There are no inhibitions but there are many expectations of others. Instinctually it expects others to provide it with the necessities and it cries to let them know.
When I think about the guardian, they are the opposite. In a proper environment the guardian cleans the baby's mess, comforts the child when it is distraught, feeds and provides love to the child. If the adult were being "real" then they potentially wouldn't provide either emotionally or physically and the baby would most definitely have defects if not die. The guardian, in a good example, understands this concept and does not want harm to happen to the baby, even if they do not necessarily like or love the baby, they provide for it.
This is maturity in my eyes. Overly simplified perhaps. I would like to expand on this later.
