From all over the world, it is quite known that first-born child (especially if it's a male/son) gets the best privilege. It may be in terms of monetary value, sanctity of name, or positions held in companies/organizations. It is believed that the first born human or animal had the purest and strongest blood, and thus were considered the best representatives of their race. This can even be traced, back in the time, long before Christ.
In a Normandy tradition (which was also brought to England in 1066), the first-born son inherited the entirety of a parent's wealth, estate, title or office; or in the absence of children, by collateral relatives, in order of seniority of the collateral line.
In a Chinese/Japanese family, there is always the present of one responsible head. It may be the grandfather, the father, or the eldest son; and it is generally the eldest son, because according to a custom of Chinese origin, the old folks usually resign their active authority as soon as the eldest son is able to take charge of affairs.
Due to expeditions or colonizations, such tradition or culture were shared among nations. It is thus long been widely accepted as a norm among societies. Up until now in our modern world, we get to see these privileges.
First-borns rule. A good example of this would be United States Presidents. Parents usually groom their first-borns for success and thus, they become natural leaders. They make their first-borns allies in managing the household, especially taking care of the other siblings.
They have a niche for details - they need to know exactly what is happening. That is probably the reason why first-borns are not just natural leaders, they are also good organizers. Other people simply trust their ability and just depend on them. It may be organizers of an event or a company. They command order and flow.
Being first-borns have its ups and downs; privilege and pressure. It all depends on the environment you were brought up, the rules that was given to you, the different persons you get to interact and the experiences you had. As you grow up, you get to learn how to manage your strengths and weaknesses. Thus, molds you into the person you are, but still its privilege (and pressure) lingers.
