Middle Child? Don't Sweat it, Birth Order Myths Busted
Anyone with siblings knows how different personality traits can clash in infuriating ways. Although the siblings may share the same parents, the same home and the same lifestyle, they can still have completely different personalities.
The belief that birth order directly affects the intelligence and personality of a person has been long held for hundreds of years. Experts and scientists have made numerous observations and theories that stereotyped people. For example, firstborns are aggressive and dominant, the youngest child is the baby of the family, and the middle child is, well, in the middle, balancing everything.
However, recent research has proven that what we have believed for so many years is a complete myth. The University of Illinois-Champaign conducted one of the biggest research regarding the correlation between birth order and personality. What the researchers found was an eye-opener - birth order has no statistically significant impact on a child’s personality.
The study, involving 377,000 high school students, found that firstborns are one IQ point higher than those who are the middle or youngest child in their families. The researchers, however, pointed out that one point is meaningless.
The researcher also showed that firstborns are more likely to be extroverted, agreeable and conscientious. However, lead researcher Brent Roberts said these differences are “infinitesimally small,” with only 0.02% of the children showing the traits.
"In some cases, if a drug saves 10 out of 10,000 lives, for example, small effects can be profound," Roberts explained. "But in terms of personality traits and how you rate them, a 0.02 correlation doesn't get you anything of note. You are not going to be able to see it with the naked eye. You're not going to be able to sit two people down next to each other and see the differences between them. It's not noticeable by anybody."
Rodica Damon, another researcher, agrees with Roberts and says that parents should stop basing their parenting style on the birth order theory.
"The message of this study is that birth order probably should not influence your parenting, because it's not meaningfully related to your kid's personality or IQ," said Damon said in a news release.
Second study confirms no birth order effects on adults
Another study had similar findings on birth order, backing up the theory that birth order has little to no effect on personality. A study from the University of Leipzig and Johannes Gutenberg University of Mainz backs the previous study. The research looked at more than 20,000 adults across the US, UK, and Germany to compare adult siblings.
The researchers looked at the ‘Big Five’ personality traits (openness, agreeableness, neuroticism, extroversion and conscientiousness) and found some conflicting results. “We found no birth-order effects on extroversion, emotional stability, agreeableness, conscientiousness, or imagination,” the researchers wrote.
They further added, “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."
Slight intellectual differences were also found; first-borns were more likely to have a rich vocabulary and less difficulty understanding abstract ideas. However, like the first study conducted by Roberts and his team, the differences were also very small and, therefore, statistically meaningless.
"The real news of our study is that we found no substantial effects of birth order on any of the personality dimensions we examined. This does not only contradict prominent psychological theories but also goes against the intuition of many people” said researcher Schnukle.
Were you born in winter or summer? Birth order may not affect your mood, but the season you were born in does
It is well-known that the seasons can affect our moods. Seasonal affective disorder (SAD) is one of the most common mood disorders triggered by the changing seasons.
During winter and autumn, people with SAD can experience symptoms of depression, such as sadness, anxiety, and hopelessness. These symptoms often lessen or disappear during the warmer, brighter seasons of summer and spring.
But what exactly causes SAD?
According to lead author Xenia Gonda, biochemical studies have found that the season someone is born in may affect their levels of dopamine and serotonin, which influence mood. These effects are long-lasting and can stay even when the person becomes an adult.
Here are other important discoveries researchers have found regarding the correlation between season and personality:
They found that participants who were born in summer were more likely to have frequent mood changes between happy and sad than those born in winter. The participants who were born in spring or summer were more likely to be positive, energetic and cheerful than those who were born in autumn or winter.
The participants who were born in autumn were less likely to have depressive tendencies than those born in winter. However, the participants who were born in winter were less irritable than those born in any other season.
"Basically, it seems that the season you are born may increase or decrease your chance of developing certain mood disorders. We can't yet say anything about the mechanisms involved. What we are now looking at is to see if there are genetic markers that are related to the season of birth and mood disorders” said Gonda.
Birth order is linked to Asthma symptoms
As studies have proven that birth order has no significant effect on someone’s personality, other studies have found that it affects some of our biological aspects. A 2008 study found that 4 year-olds with older siblings are more likely to suffer from respiratory problems, and children who had at least two older siblings are 50% more likely to suffer from breathing problems than those who do not have.
"Our findings support the hypothesis that having older siblings increases a child's risk of exposure to infectious agents before age two years, and in turn increases the child's risk for wheezing," said Matthew Perzanowski, PhD, lead author and assistant professor of Environmental Health Sciences at the Mailman School of Public Health.
The prevalence of the wheeze was higher among boys (32%) than girls (21%) and much higher among children with asthmatic parents (53%) than those without (22%). One of the possible explanations for the symptoms is that the children with older siblings are being exposed more often to respiratory infections at an early age.
"Previous findings of the opposite association between asthma and birth order among older children and adults have served as the basis for what is called the hygiene hypothesis, the idea that exposure to infectious agents at a very young age reduces the risk of asthma in the long term. Only by continuing to follow these children can we determine whether and how birth order predicts diagnosed asthma and asthma that persists throughout childhood," noted Inge Goldstein, senior author of the study.
"But even if the patterns of association change as the children grow, we have learned from this study that four-year-olds with older siblings are more likely to experience respiratory symptoms that burden them and their families and impose the costs of care on them and the community," commented Judith Jacobson, DrPH, principal investigator of the study, which was funded by the National Heart, Lung, and Blood Institute.
This information could be used to help predict which children are more likely to suffer from asthma symptoms. It means that doctors can intervene early and make sure that children who are prone to respiratory problems will receive the care that they need.
First-born children have a higher risk of developing diabetes
If the previous study showed that the younger siblings are prone to asthma, another study has shown that firstborns are more likely to develop diabetes that their younger siblings.
The study, which was conducted at the University of Auckland’s Liggins Institute, discovered that first-born children may have a higher risk of developing diabetes or high blood pressure than their siblings.
Researcher Wayne Cutfield said, “Although birth order alone is not a predictor of metabolic or cardiovascular disease, being the first-born child in a family can contribute to a person’s overall risk.”
How does this happen?
Researchers believe that the changes may have happened while the child is in utero. After the first child, the mother’s body may have an increased flow of nutrients to the fetus. This would be beneficial to later children but a disadvantage for the first child. However, more research needs to be done to find out if the effects continue into adulthood.
“Our results indicate first-born children have these risk factors, but more research is needed to determine how that translates into adult cases of diabetes, hypertension and other conditions,” Cutfield said.
First born children are more likely to be near-sighted
Diabetes is not the only problem for firstborns but poor eyesight as well. This was according to a new study which found that the environment a child is raised in may contribute to their health – specifically, their eyesight.
First born children often feel more parental pressure to achieve more than their younger siblings, which means they spend more time studying and reading. As the study has discovered, first born children are 10% more likely to be myopic than their siblings, and 20% more likely to be severely near-sighted.
"In the current study we set out to test whether the link between birth order and myopia might have arisen because first-born individuals tend to spend slightly longer in full-time education than later-born individuals," says study lead author Jeremy Guggenhem of Cardiff University in Wales.
"Greater educational exposure in earlier-born children may expose them to a more myopia genic environment; for example, more time doing near work and less time spent outdoors," the researchers said.
If you want to lower the chance of your firstborn child becoming near-sighted, set boundaries regarding the amount of time they spend online or studying. Encourage your child to play outside, and make sure that they take regular breaks when studying or reading.
New studies have indeed proven that birth order has nothing to do with the personality trait of a person. However, the birth order can affect a child’s health, such as firstborns are more prone to diabetes and high blood pressure while younger siblings are more likely to be asthmatic.
First-born children are more likely to be near-sighted, but this is due more to environmental reasons rather than biological. Lower the chances of your child becoming near-sighted by making sure they take regular breaks when they study or read.
A. Ayyavoo, T. Savage, J. G. B. Derraik, P. L. Hofman, W. S. Cutfield. "First-born Children Have Reduced Insulin Sensitivity and Higher Daytime Blood Pressure Compared to Later-Born Children." Journal of Clinical Endocrinology & Metabolism, 2013; DOI: 10.1210/jc.2012-3531
Columbia University's Mailman School of Public Health. "Birth Order Linked To Asthma Symptoms." ScienceDaily. ScienceDaily, 11 May 2008. <www.sciencedaily.com/releases/2008/05/080508164634.htm>.
European College of Neuropsychopharmacology. "Birth season affects your mood in later life, new research suggests." ScienceDaily. ScienceDaily, 18 October 2014. www.sciencedaily.com/releases/2014/10/141018205411.htm
Julia M. Rohrer, Boris Egloff, and Stefan C. Schmukle. "Examining the effects of birth order on personality." Proceedings of the National Academy of Sciences, 19 October 2015 DOI: 10.1073/pnas.1506451112
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Rodica Ioana Damian, Brent W. Roberts. "The Associations of Birth Order with Personality and Intelligence in a Representative Sample of U.S. High School Students." Journal of Research in Personality, 2015; DOI: 10.1016/j.jrp.2015.05.005