When a hatch-ling grows up , learns everything he/she can learn under the protection of the parent bird , the parent pushes the adult bird out of it's nest so that it can go and build it's own legacy or form it's own family.This is the case not only for birds but for every other animal or fish.Since human beings are also animals , we are also supposed to follow this law of nature.In the west they adhere by these laws unlike us.We tend to cling onto the protection of our parents for a bit longer,yet eventually even we leave the nest only they do it a little earlier.Now what's wrong in that? Isn't 18 the official age for proclaiming an individual as an adult.