HR · 21 July 2015

Are older siblings more likely to be successful? Probably not

A new study suggests that birth order doesn’t have a significant impact on personality traits, despite popular assumptions

There have been numerous queries as to whether being the older or younger sibling sets you up to possess certain qualities, and indeed, whether these make you more or less likely to be successful. Now a new study examining the benefits of birth order suggests people may have been worrying about nothing. It found that while eldest children do possess different personality traits to their younger siblings, the differences are so minimal that they’re essentially negligible.

Brent Roberts, a psychology professor at the University of Illinois, who carried out the study, said differences from birth order are “infinitesimally small”, working out at a correlation of 0.02.

“In some cases, if a drug saves ten out of 10,000 lives, for example, small effects can be profound. But in terms of personality traits and how you rate them, a 0.02 correlation doesn’t get you anything of note. You’re not going to be able to sit two people down next to each other and see the differences between them,” he explained.

Previous research has thrown up various predictions about what birth order will mean for individuals’ future prospects and whether people possess certain attributes that make them better to work with or for, but the study’s co-author, Rodica Damian, said such research has suffered from small sample sizes, non-representative participant pools or failures to control for factors like socio-economic status.

The University of Essex looked into birth order last year, with data from over 3,500 brothers and sisters, concluding that firstborns were seven per cent more likely to want to stay on in education.

It claimed that “firstborns have an educational advantage over their later-born counterparts”. It added that birth order is “clearly a within-family phenomenon”, and sought to look into birth order effects on educational attainment under a within-family design.

The results indicating that firstborns tended to achieve a higher educational level was partly due to “an indirect effect mediated by the effects of birth order on aspirations” – that the eldest sibling often had higher aspirations leading to higher educational levels.

Virgin founder Richard Branson, who has two younger sisters, said he thought leadership skills may be cultivated among older siblings at a younger age, as they’re often “given the responsibility of looking after younger siblings”.

He was less convinced that birth order has a significant impact in terms of future success, saying “whether you’re firstborn or 15th born, if you are given support and mentorship and have a desire to make a difference in the world, you can become a leader”.

When considering traits of different siblings, Frank Sulloway, an adjunct professor at UC Berkley who has studied birth order from a Darwinian perspective, said that the younger sibling personality is risk-taking and adventurous, which may line up with characteristics you’d typically associate with an entrepreneur. He added that younger siblings often look outside the box, to find alternative ways of “deriving the maximum benefit out of the environment, and not directly competing for the same resources as the eldest”, and as a result may be the source of more innovation.

The newest study is an extensive one – Damian said its examination of 377,000 American teenagers was “by far the largest study of birth order and personality”. The researchers found that firstborns do have slightly higher IQs than their siblings, but this is only one point higher, which is statistically significant but a practically meaningless difference.

Similarly, eldest siblings scored higher on personality traits including extroversion and conscientiousness, but the association was small enough to be well below the level of perception.

Image: Shutterstock

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ABOUT THE EXPERT

Rebecca is a reporter for Business Advice. Prior to this, she worked with a range of tech, advertising, media and digital clients at Propeller PR and did freelance work for The Telegraph.

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