A study reveals that the order of birth among siblings has an impact on the development of intelligence.

Sibling relationships are surrounded by many preconceived ideas. According to these clichés, the eldest are the most serious and responsible children, the youngest are renowned for their ability to restore calm and peace and the youngest are the most creative of the siblings. However, the existence of these personality traits is based more on preconceived ideas than on real theories. The question of the impact of birth order on individuals is a subject that has interested German psychologist Julia Rohrer, who works at the University of Leipzig. Together with two colleagues and based on previous studies on the subject, she established a report with clear results.

His study focuses on the effects of birth order on individuals. Researchers looked at different personality traits like intelligence, extroversion, emotional stability, agreeableness, conscientiousness, and imagination. As Julia Rohrer explains to the Guardian, these aspects of character come from the five personality traits that serve as a basic measure of personality in psychology: extroversion, emotional stability, agreeableness, conscientiousness, and openness to experience.

The most significant results concern intelligence. The study finds that “firstborns obtain better results in terms of intelligence”. The group of researchers demonstrated that older adults have, on average, a higher IQ than their younger counterparts. In detail, the study indicates that in the sample formed by families composed of two children, “an older child chosen at random had a 52% chance of having a higher IQ than a younger child chosen at random”. Experts add that “in two-person siblings, the older brother had a higher IQ than his younger brother in 6 out of 10 cases.”

Speaking to the Guardian, Julia Rohrer explains that a child’s personality, like consciousness, evolves with age. The eldest being by definition older, it is therefore logical that he evolves before his brothers and sisters. The psychologist indicates that clichés about the eldest are born more from this age factor rather than from their place among siblings. Ms. Rohrer also highlights an argument from another study carried out on the subject in the United States by two professors from the University of Michigan. The latter argue that the more developed intellect of elders can be explained by the fact that they naturally adopt a role of “teacher” which is more stimulating than the role of “student” in which the younger finds himself.

The psychologist specifies that the results obtained by her study are particularly valid for Western societies, but can be radically different in other contexts. A similar study conducted by the group in Indonesia demonstrated that in a good number of cases, the eldest child must end his or her schooling to find a job.