Who is the most unusual person in my family?

Donny, who is the most unusual person in my family, is my little brother. He has a different personality compare to my parents and me. For example, I like to social with friends, and my personality is extrovert. Also, I usually talk a lot. However, my brother's personality is introvert, and he doesn't like to hang out with too many people. Also, he is really quiet. Do you know what kind of situation he will talk? When you ask him a question, at that time he will talk. Therefore, in other time he won't open his voice. In addition, this spring break I went back my country to see my family. Especial my brother didn't talk more than five sentences. I have no idea about that. He just too silence. Many people think that my brother and I come from different family and parents. Yeah, maybe I was adopt from my parents. They might pick me up under the bridge. Ha ha......