Imagine a world in which nobody has any brothers, sisters, aunts, uncles, nephews, nieces or cousins.As far as the overpopulation goes, I think China was on the right track with the one child policy...Forced sterilization after one child would make for a lot less suffering.
A world in which girls are aborted since boys are more productive.
A world in which children have emotional and developmental problems from only having adults to play with.
A world in which children have families consisting of two parents, four grandparents, and maybe a few great grandparents.
A world in which children are pampered to the point that they grow up to be "Little Emperors" that are over-indulged, lack self-discipline and have no adaptive capabilities: https://en.wikipedia.org/wiki/Little_Emperor_Syndrome
A world in which babies that don't meet parents' expectations are euthanized so they can try again.
After creating such a world, China realized their mistake and abandoned their "One Child Policy"