Well, it looks like I owe my firstborn sibling a few dollars from a bet we made many years ago. How was I supposed to know that my older and now confirmed wiser brother was right when he told me that he was smarter just because he was the oldest? Obviously, I’m not as smart.
According to a new study published in the Journal of Human Resources, my brother and all of the other firstborn siblings out there may finally be able to claim that they can score higher on an IQ test than their much younger siblings.
The study authors analyzed data from the U.S. Children of the National Longitudinal Survey of Youth (assembled by the U.S. Bureau of Labor Statistics) on nearly 5,000 children followed from pre-birth to age 14. They found that as early as age 1, latter-born children (like myself) score lower on cognitive assessments than their siblings, and the birth order gap in cognitive assessment increases until the time of school entry and remains statistically significant thereafter.
So why the lower scores for younger siblings? The authors found that mothers take more risks during pregnancy and are less likely to breastfeed and to provide cognitive stimulation for latter-born children. In other words… moms tend to relax when it comes to the second, third and fourth child.
Variations in parental behavior can explain most of the differences in cognitive abilities before school entry. The findings suggest that broad shifts in parental behavior from first to latter-born children are a logical explanation for the observed birth order differences.
Translation: Firstborn children received more mental stimulation and support in developing thinking skills from their parents during their early years compared to younger siblings who were offered less mental stimulation and took part in fewer activities such as reading, crafts and playing musical instruments. And while this doesn’t necessarily mean you need to run out and sign your younger children up for tons of art and music lessons or start reading to them for hours at a time, it does indicate that you should, you know, do a little more of that.