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Older equals smarter? Maybe not, according to studies on birth order

Older equals smarter? Maybe not according to studies on birth order - Sage Institute of Child CareAre there are any advantages to being the eldest child? Are you a more conscientious, high achieving first born, or a more agreeable, altruistic later born?  Debate continues about the validity of these long-held stereotypes, but recent large-scale studies suggest that birth order is almost meaningless when it comes to personality – and intelligence.

Over the years there has been much research into the influences of birth order on an individual’s personality traits, intelligence and even health.  The idea that birth order determines siblings’ personality and intelligence remains pretty entrenched with historical studies, expert debate and even individual family’s anecdotal evidence fuelling the theories.  But overwhelmingly, modern scientific findings on the matter have proven inconclusive.

While it may be fun to draw generalisations about your siblings’ birth order and resulting personality traits, recent studies suggest that birth order doesn’t make that much difference when it comes to personality, and has only a very small influence on intelligence.

The evolutionary view of birth order

One long-held way of looking at birth order is called the “evolutionary view”. This suggests that as siblings naturally compete for their parent’s attention, they develop different ways of doing so based on their birth order.  Traditionally the evolutionary view holds that first born children are physically stronger and more mentally developed than their younger siblings, but being threatened by the arrival of brothers and sisters may be more neurotic.  They are also more prone to being dominant and therefore better leaders.  The middle child will learn from the older child and therefore become more extroverted and agreeable but can also be independent and even rebellious.  Convention holds that the youngest child might be spoiled and immature, but outgoing.

I’m sure that many of us can relate to these stereotypes, and you may have even discussed this with your family or siblings. We love to sort ourselves into categories, whether they have a scientific basis or not – it’s human nature to want to define and place things in logical order. It helps us understand our complex world and let’s face it, it can be fun.

These stereotypes are not well supported by modern studies, however. If these effects did exist, they would logically be more pronounced in younger children still living together and competing for their parent’s attention. Right? Or perhaps not. The results of a recent study, published in the Journal of Research in Personality examined 377,000 high-school students in the US and found little evidence of birth order influencing personality traits.

This research focused on the main personality traits of openness, agreeableness, neuroticism, conscientiousness and extraversion.  The researchers hypothesised, based on the evolutionary view, that first born children should be higher in conscientiousness, neuroticism and the dominance aspects of extraversion, and that subsequent siblings should in theory be higher in agreeableness and the sociability sides of extraversion.

The evolutionary view of birth order - Sage Institute of Child Care

The results didn’t always support the hypotheses, however. The data from this large study sample revealed that first born children were a bit more conscientious and dominant, and less sociable, which fits the stereotype. But researchers also found that first borns were more agreeable and less neurotic than other siblings, which contradicts the stereotypes. The differences, however, were very small, so much so that if you tried to identify the same pattern in a smaller sample size, they wouldn’t even show up.

“We would have to say that, to the extent that these effect sizes are accurate estimates of the true effect, birth order does not seem to be an important consideration for understanding either the development of personality traits or the development of intelligence in the between-family context.”

When looking at intelligence, the first born children did come out slightly higher than subsequent siblings, but again it was very marginal – only one IQ point. The researchers summarised that “We would have to say that, to the extent that these effect sizes are accurate estimates of the true effect, birth order does not seem to be an important consideration for understanding either the development of personality traits or the development of intelligence in the between-family context.”

Older, wiser, smarter?

The eldest child may sometimes appear smarter, or at least more confident. But how much smarter are they? Not a lot. Scientists from Leipzig University carried out another large study involving results from three national studies, involving more than 20,000 people in total and found that there was a 1.5 drop in IQ points per sibling when compared to the first born. Hardly earthshattering stuff.

About personality, the researchers stated in conclusion: “All in all, we did not find any effect of birth order on extraversion, emotional stability, agreeableness, conscientiousness, or imagination…”

“All in all, we did not find any effect of birth order on extraversion, emotional stability, agreeableness, conscientiousness, or imagination…”

Perhaps of more interest were the differences that revealed how intelligent individuals thought they were. First born children were comfortable with statements such as “I am quick to understand things” far more than their younger brothers and sisters. They were also more likely to announce that they found it easier to grasp abstract ideas and said that they had a broader vocabulary than their siblings.

The jury is still out as to why this might be the case. However, other research papers suggest that this confidence could be down to nurture – not nature – with the eldest child’s social status within the family being the likely cause. This social rank may also be the reason for the child’s ever so slight increase in intelligence.

All things in consideration

While birth order is often invoked as an important variable to explain the development of personality and intelligence within families, modern research shows that there is likely to be a whole lot more at play than just birth position.

We’ll let you draw your own conclusions, but if you’re still wondering about birth order and intelligence, perhaps it’s best not to ask your older brother or sister about it!

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Vicki Tuchtan

Vicki Tuchtan

Vicki Tuchtan is the Academic Director at Sage Institute of Education. She oversees learning processes, teaching outcomes, resources and course development. A passionate advocate for bettering standards of training in Australia, she is currently writing her PhD thesis on defining quality training in the Australian vocational education sector.
Vicki Tuchtan

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