Actually their interference is the least influencing reason behind his detachment and they believed that it was to avoid causing him unnecessary pain or worry, but it did stunt his growth as a person for a while and even he was aware and allowed it; the main causes of his detachment are that he...
That's something I like about Makoto, he has some really strong sociopathic tendencies yet he tries to deny them and become a "normal person" but a normal person in his eyes is a really selfless philanthropist, so he is dealing with the problems caused by either his ignorance of what truly means...