Are you the oldest or youngest child? Are you in the middle or an only child? Many phychologists believe that your position in your family helped to shape you and your relationship others. As a newborn, you quickly developed a relationship with your parents and later, while you were growing, you formed relationships with your siblings. According to psychologists, your birth order affected how your parents and your brothers and sisters reacted to you and treated you. That is, you and they behaved in certain ways depending on your position in the family. All of this strongly influenced your development, and in turn, influences you as an adult: what you think about yourself now and how you react to and treat others.