In 1982, “The Birth Order Book” by psychologist, Dr. Kevin Leman, was published and quickly became a best seller. The premise was that there are four personality types based on a person’s birth order. Since then, other authors have written extensively about whether one’s birth order has a lasting effect on our personalities, IQ, successes or failures in life and other physical, emotional or psychological traits.
Now, a large study from the University of Illinois says there may be a slight benefit to being the first born in a family, but the difference is miniscule and offers no real advantage or disadvantage in how a person’s life plays out.
Psychology professor Brent Roberts, along with former postdoctoral researcher Rodica Damian, conducted an analysis of 377,000 high school-age students to test the assumption.
The researchers found that first-born children do tend to have a slightly higher IQ and often display differing personality traits than their siblings later, but the differences are so small between the first- born and the later-born that they really have no significant impact on their lives.
Their analysis determined first-borns had a one-point IQ advantage over their following siblings, statistically significant in scientific terms but meaningless in suggesting any practical effects on a person's life.
Previous studies have been conducted on the same topic, but most had a small sample size – that’s why Roberts believes this study is noteworthy.
"This is a conspicuously large sample size," he says. "It's the biggest in history looking at birth order and personality."
Looking at personality differences, the study found first-borns tended to be slightly more extroverted, conscientious, agreeable and less anxious that later-borns, but that those differences were on a scale of 0.02, or "infinitesimally small," Roberts notes.
Statistical differences can be more or less valuable depending on what is being examined.
"In some cases, if a drug saves 10 out of 10,000 lives, for example, small [statistical] effects can be profound," Roberts said. However, he noted, when it comes to personality traits a 0.02 difference is so small as to be invisible, something that wouldn't be apparent to 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," he says. "It's not noticeable by anybody."
Damien, who is now a now a professor of psychology at the University of Houston, says she and Roberts controlled for factors that might skew results, including a family's economic level, the number of siblings and their relative ages.
Whether a child’s birth order has any effect on his or her personality or IQ is still somewhat controversial among child psychologists and psychiatrists. Some believe it has its place in child rearing and others think it is simply pop culture. Most would probably agree however, that a child’s later personality and IQ are typically based on more complicated factors than whether they were the first, middle, last or only child in the family.
The study was published in the Journal of Research in Personality.
Source: Jim Algar, http://www.techtimes.com/articles/69519/20150716/birth-order-has-no-effect-on-iq-or-personality-massive-study-finds.htm