Protective parents will make you miss what is in the social world. Although they protect their kids from bad influence, in the process they forget that they need to be free in order to know what is in the outside world. This makes the kids not to be able to make their own decisions.
One of the negative effects of a parent being overly protective (key word, overly) is that their children will pull away from them and start hiding things or be less likely to trust them. At least that was my experience with overly protective parents. :)