why do children think...parents as their enemy?

It is called the generation gap. Children when grow up start thinking at their own level, they think that they are wiser and smart enough and when they are encountered by their parents and are told that they have lot to learn in life they start thinking that their parents are their enemies.

Because they think that nothing is right in the eyes of their parents... Even though they think that their parents are their enemies... the good thing is that they still obey and give respect to their parents.

ah yes, the age old question:P ... well it's from both sides, mostly it's psichologic, parents think they know what's best and are bossy and children think they know what's best and hate being bossed around ... just as here if someone has a different opinion than a point of view u care about u become annoyed, only difference is that you have to live with the person a quarter of your life so hate can be easily constructed if opinions differ a lot, as is in parent child relations the different experiences almost always make different opinions and lead to other stuff, that and from past things parents never listen to children and children never listen to parents so it comes to a point where no matter who is right the other rebels against it