The idea goes back to Plato's Republic. Very odd how many believe Plato's notions of an ideal republic would actually be anything other than a nightmare. Sometimes I wonder whether Plato was being critical of Socrates and whether this is why he used Socrates as a mouth piece. . . but that's just an entertaining fantasy.

I have experienced being raised by family until 13 and then in foster care, and I have met others with similar experiences. Nothing could be more brutal than the sort of treatment one receives from those who don't see you as family. Doesn't take much for them to cut you off, and gives rise to the sort of troubled psychology you'd expect. Arguably this is not the same as the communal raising of children, but surely there are lessons to learn from it. The fallacy is that one would feel the same deeply committed way toward all the kids in the community as toward one's own. Instead, one feels less not more commitment toward the whole.