I don't think people should kick their kids out at 18 but they should prepare them for independence. Helping your child is different than enabling them.

I know parents who charge their children rent after they turn 18, for example, and who made sure the children were sharing in household chores from an early age, in age appropriate ways. At the same time, the parents provide a safety net for their kids and will do things like providing matching funds for when the child wants to buy a car.

One friend of mine had his college expenses covered by his parents but in return they insisted he keep at least a B average. Another friend was working as a teacher and her parents bought her a good used car when hers died. She appreciated this greatly but years later, she was so proud when she could afford to buy her own new car.

I have a cardinal family that makes its nest in my back yard each year. The parents continue to feed their babies after they learn to fly - I often see the male adult putting seeds into his fledgling's mouth. Yet, the parent birds do expect their young to leave the nest. Sure, they still care for them but not in the same way they did right after they hatched.

In many European countries, there are long term problems because children stay home too long. Italian men, for example, are stereotypically mama's boys, and this can make it harder for them to start their own families. Perhaps this is one reason Italian birth rates are so low that they can no longer replace their population.