There are correlation and between birth order and aspects such as temperament and behavior. There is the hypothesis that developed. First-born children do not have to deal with siblings and related problems. They tend to find the process of peer socialization; also they have some personality traits. They are also having been found to be more responsible and assertive to positions of leadership than those born in other birth-order.

Second born demonstrate markedly different tendencies. They tend to feel inferior to the older child because it is difficult for them to comprehend that their lower level of achievement is a function of age. They try to succeed in siblings excel. They are also tend to be better at diving and archery.

The last born child is the one who tends to be the eternal-baby. They demonstrate the highest level of self-esteem. They often exhibit less competitiveness than older brothers and are more likely to take part in sororities and fraternities.

Only children exhibit a lower need for affiliation than other children.