If you are an overprotective parent, your child has probably been an "inside" child and has not had a chance to socialize too much without you being right there! This leaves many effects on the child.
~They second guess themselves in decision making because they are used to being led and instructed by their parents.
~They are emotionally unable to feel like they are in control of their lives and decisions due to the parents always deciding for them.
~Socializing with other kids is tough because they are not used to the normal traits of a child (pushing, pulling, teaming up, yelling, climbing trees, risque behavior)
~Even when willing to jump around and participate in an activity with a group, they can't because mom always said "no, you will brake something".
All of the above are a cause for other kids to assume that he is a a 'scaredycat' and they most likely won't want to play with him again.