We all seemed to believe that the youngest sibling in the family is a spoiled brat while the older ones are more disciplined and more responsible. Maybe because the parents are getting tired of spanking and reprimanding their younger children, which is unfair for the first child to take all harsh disciplinary action.

Anyway, proposed his observance that there is a huge impact on a child's development in accordance with the position in a family. The oldest children are more conscientious and neurotic while the youngest are more open to new experiences. The firstborn children are reliable, well-behaved, and seem like the small version of their own parents. The middle children are more understanding, cooperative, flexible, competitive, more favor in fairness, and more likely to pick intimate friends who might become their extended family because the attention they are seeking lacks in their family of origin. Lastly, the party-pooper youngest children gain more freedom than their siblings because their parents made them feel special and entitled and have fewer responsibilities.

However, it is not scientifically proven that it is true. If that would be the case, then all successful people are first-born child but it is not. But when it comes to IQ, researchers found a slight difference among the siblings. The first child tends to have a higher IQ than the latter children. Perhaps in their early life, they gain more extra parental attention so they are more supported in doing mental tasks. And it is a good thing if the parents of those children both died from an unfortunate event, then the eldest will replace them and can be smart and responsible enough to take good care of his or her younger siblings, perhaps by pushing them to the deep empty well or sell them as slaves just to inherit the huge amount left by their deceased parents.