From Cain and Abel and the Karamazov brothers to Cinderella, the warmth and support of siblings are hardly taken for granted.
Now researchers have found that children who complain about their siblings may have good reasons to complain: The more siblings teens have, the more it hurts their happiness, they claim.
A study of high school students in the US and China found that children from larger families had slightly worse mental health than children from smaller families. The greatest impact was seen in families with multiple children born less than a year apart.
Doug Downey, a professor of sociology at Ohio State University, said previous research in this area revealed a mixed picture of positives and negatives for children with more siblings, adding that the latest results were “not a given.” ”.
The researchers asked 9,100 eighth-graders in the US and 9,400 in China, with an average age of 14, a series of questions about their mental health, although the specific questions varied from country to country. In China, teens without siblings fared best in terms of mental health. In the US, children who had no siblings, or just one, were found to have similar mental health.
Overall, mental health was worse the more siblings teens had, with the effects being greater for teens with older siblings, and when siblings were close in age.
Writing in the Journal of Family IssuesDowney and his colleagues argue that the findings are consistent with the explanation of “resource dilution,” the driving force behind the unwritten formula that states that the number of dropped balls increases, sometimes dramatically, with the number of siblings born.
“If you think of parental resources as a pie, one child means they get all the pie,” Downey said. “But adding more siblings means each child gets fewer resources and attention from their parents, and that can impact their mental health.” That teenagers did worse when their siblings were the same age supports this idea, the researchers believe.
But there are other possible explanations. For example, the teens with the best mental health came from families with the highest socioeconomic advantages. In the US, these were often families with only one or two children. In China it was families with one child. In accordance with China’s one-child policy, about a third of Chinese children were only children, compared to 12.6% of American children.
With the rise of “one and done” families, researchers increasingly want to understand the impact of siblings on mental health and other factors. Previous studies suggest a range of positive effects associated with siblings, suggesting a complex picture of benefits and harms.
Previous work by Downey showed that children have more siblings got along better with others at daycareand were less likely to get divorced later in life – perhaps because they already had some experience navigating close relationships. Meanwhile, a Study from 2016 of more than 100,000 Norwegian children over the years found better mental health in larger families.