For example if a family has two daughters then has two sons, the first daughter and the first son will be treated as firstborns.
Nearly half of all U.S. presidents were firstborns; only four were lastborns.
Firstborns often choose professions that require precision, such as careers in science, medicine, law, engineering, computer science, or accounting.
Firstborns can harbor some resentment toward siblings because parental attention has to be shared.
If this does not bring the attention they want, some firstborns defy authority and misbehave or rebel.