Are you the eldest and wisest child in your family? Or perhaps you are the youngest and most rebellious? The birth position among siblings has long fascinated both scientists and the general public.
Many people believe that the position among our siblings comes with specific personality traits, but research has proven that these stereotypes do not always fit in the frame.
In a study done by the University of Leipzig, researchers examined the effects of birth order among 20,000 people from the USA, UK and Germany. They analyzed the participants through empirical tests on intelligence, and they also examined how neurotic, extrovert, conscientious, open, agreeable, and imaginative the participants were.
When they compared the results to their birth position, they concluded that first-born children are indeed more intelligent than the later-born children.
However, the tests failed to prove that birth position had any effects on extroversion, emotional stability, agreeableness, conscientiousness, or imagination.
When it came to the IQ tests, the researchers found that there was a specific pattern that showed an approximate 1.5 IQ points increase in intelligence in birth-order position. In other words, the first-born child would have 1.5 IQ points more than the second-born.
Of course, this was not always the case. The results showed that in a family with two children, the first-born is 60% likely to be more intelligent than the second-born.
Is this IQ difference innate, or developed?
As you may have already heard, most of our intelligence is developed. In fact, only around 40% of our intelligence is genetically conditioned. The rest needs to be built through the environment. The IQ differences between the children comes as a result of environment, not genes.
The first reason first-borns can have a higher IQ may be due to the fact that these children get undivided attention for at least some months or years – something late-borns will have to share from the beginning.
The parents’ expectations from their first child are often higher compared to the other children, and as you know, higher expectations contribute to higher IQ in the long run.
Because of this, first-born children also find themselves often looking after their younger siblings. They are often designated the role of teaching their younger brothers and sisters what has been taught to them.
This responsibility has the greatest effect on the IQ boost first-borns get. Perhaps those 40% who didn’t have a higher IQ in the study were not given such responsibilities by their parents.
Is this the case with you and your siblings?