Birth Order Link to Personality & Intelligence Unfounded: Study

It is common to hear that firstborn children are always tagged as the responsible and smart ones, while the middle and last-born children are considered as more easy-going and rebellious. But, according to a new study, birth order has nothing to do with personality or intelligence development of individuals.

Business Insider writes that based on an experiment conducted by psychologists at the University of Illinois, with 377,000 high school students observed, firstborn children showed an IQ advantage of just one point when compared to their other siblings. It has also showed an insignificant difference when it comes to personality development.

Prof. Brent Roberts, lead author of the study, explained that with the findings of the study, what Alfred Adler has stated in the early 20th century may be guaranteed a 0.02 correlation only, making it of no value at all.

Medical Xpress adds that this may be relevant to other studies, like how a drug can save 10 out of 10,000 lives. But when it comes to personality and traits, the effects of the difference cannot be fully seen by the naked eye. You can't easily see even if you let two different subjects seat side-by-side then compare them.

Rodica Damian, a professor of psychology at the University of Houston and Prof. Roberts' co-author, said previous studies of birth order have been compromised by sample size, family's economic status and age gap between the siblings.

An ideal study process would be to follow all the families over time, to collect the IQ and personality data of each child when they reach a specific age. 

The researchers have also evaluated smaller families with only two siblings. This has allowed the researchers to look for the differences between each child and to confirm what they have seen in a larger scale. But, as with the bigger study, findings are still deemed insignificant.

Business Standard reports that the study has been the biggest birth order research ever conducted, making the analysis more accurate and more effective as it has dealt with a bigger coverage.

The researchers wish to express to parents that birth order should not influence their parenting style and how they treat their children as each child is different from one another.

The analysis has been published in the Journal of Research in Personality. It can also be viewed online through the Science Direct website.