Bigger families may lead to worse mental health in teens, as shown by a study in the United States and China. The details differ based on factors like age gaps between siblings, but the overall trend is the same in both countries. Doug Downey, the study’s lead author and a sociology professor at The Ohio State University, finds the consistency across countries notable.
Downey said, “Our results couldn’t have been easily predicted before we did the study. Other studies have shown that having more siblings is associated with positive effects, so our results were not a given.”
Downey and Rui Cao, a sociology doctoral student at Ohio State, conducted a study recently published in the Journal of Family Issues. They examined data from over 9,400 eighth graders in China and over 9,100 in the U.S. The average Chinese youth has fewer siblings (0.89) than the middle American youth (1.6). Due to China’s One Child Policy, about 34% of Chinese children are only children, while only 12.6% of American children are. The researchers, asking different questions in each country, assessed students’ mental health around 14 years old.
In China, teens without siblings had the best mental health, while in the U.S., those with no or one sibling had similar mental health. Some issues could only be studied using U.S. data. Results in the U.S. revealed that both half and full siblings are linked to poorer mental health. Having older siblings and closely spaced siblings in age had the worst impacts on well-being.
Siblings born within a year of each other had the most substantial adverse effect on mental health. According to Downey, the findings align with the idea of “resource dilution,” where more siblings mean less attention and resources from parents.
“When there are more siblings, each child gets less attention and resources from parents, possibly affecting their mental health,” explains Downey. The negative impact is highest when siblings are closely spaced, competing for similar parental resources. Another idea is that families with many children may differ in ways that affect their kids’ mental health, known as the selectivity explanation.
However, the differences between China and the U.S. somewhat support this. In both countries, children from families with more socioeconomic advantage had better mental health. Yet, the overall results indicate that the selectivity explanation only partially explains the situation.
Downey said, “What we found is that when you add all the evidence up, the effect of siblings on mental health is more on the negative side than the positive side.”
Downey pointed out that the data doesn’t reveal the quality of sibling relationships. Better sibling relationships are likely more beneficial and positively affect children’s mental health. Despite this study showing a negative impact, other research suggests that having more siblings is linked to improved social skills in kindergarteners and a lower likelihood of divorce in adults.
Downey emphasized the need to learn more about the impact of siblings, especially since the U.S. and other countries are experiencing lower fertility rates. Understanding the consequences of growing up with fewer or no siblings is becoming an increasingly important social issue.
In conclusion, the study led by Professor Doug Downey suggests that having more siblings is linked to poorer mental health in teenagers. The research in both the United States and China points to a negative impact on mental well-being, especially when siblings are closely spaced. While there is still more to learn about sibling dynamics, this study highlights the importance of understanding the consequences of growing up with fewer or no siblings, especially as family structures evolve in the changing social landscape.
Journal reference:
- Douglas B. Downey, Rui Cao, et al., Number of Siblings and Mental Health Among Adolescents: Evidence From the U.S. and China. Journal of Family Issues. DOI: 10.1177/0192513X231220045.