New study further explores birth order impact on personalities

A new research unpacks the myths and theories prevalent in various studies analysing the ‘firstborn effect’ and explores potential explanations.

According to a recent Swedish study, firstborns have more favourable personality traits, including openness to new experiences, conscientiousness, extroversion, friendliness and greater emotional stability, than their later-born siblings. As a result, they are more likely to become chief executives and senior managers, whereas later-born children, who love to take risks, often end up being self-employed.

Firstborns tend to possess psychological characteristics related to leadership, including responsibility, creativity, obedience and dominance. They are also more likely to have higher academic abilities and levels of intelligence than their younger siblings. These qualities are believed to make firstborns more successful. But the “baby” of the family is more likely to take risks, rebel, show addictive behaviour and lack independence compared with their older siblings.

There are two explanations that could justify this firstborn effect. From the evolutionary perspective, parents favour and invest (shelter and food) in their firstborn to increase their chances of survival and reproduction. But this comes at a cost because the parent is now unable to invest the same amount of resources in later-born offspring.

Younger siblings then have to compete for these limited parental resources and attention. (So parents who spend less time helping their later-born children with schoolwork may do so because of the lack of spare resources.)

But children who are born last often receive preferential treatment. This is because parents now have the last chance to invest their resources. They are also older and tend to have more money at this point. Parents are more likely to invest in the education of their latest-born offspring.

Parental expectations could also explain the more favourable personality traits among firstborns. That is, parents tend to be stricter in their parenting with the firstborn. Parents also encourage toughness because firstborns need to act as role models (and surrogate parent) for their later-born siblings and defend the values of the parents.