In general, most people tend to believe that parents are the most influential in children's developmentand certainly they are sometimes right, because children spend more time with their parents than their classmates.
... I wish you had a break and expressed this idea in two sentences;
In general, many people tend to believe that parents are the most influential people in their children's development. They are right because children spend most of their time with parents than with anyone else.In my opinion, classmates encourage some attitudes and sometimes help a child to define his/her character.
... First, you should express your opinion in the introduction and not in a body para. Also, your introduction gives an impression that you hold the opinion that parents have the best influence on their children. This is a bit contradictory :(