Why having more siblings means poorer mental health for teens: study

Siblings can be your best friend — or worst nightmare.

The more siblings a person has, the weaker their mental health is, a new study published by the Journal of Family Issues found.

A research team from the United States and China analyzed data from thousands of eighth graders and assessed their mental health to determine the impact having siblings had on their well-being.

“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,” Doug Downey, lead author of the study, said in a statement.

In China, only children reported the best mental health, while in the United States, those with no or one sibling had similar mental health.

Those with the worst mental health were those with older siblings and siblings close in age, the US data found.

But it doesn’t seem to be the name-calling or hair-pulling that worsens teens’ mental health.

The experts believe that more siblings leading to poorer mental health is largely due to “resource dilution.”

“If you think of parental resources like a pie, one child means that they get all the pie – all the attention and resources of the parents,” Downey explained.

“But when you add more siblings, each child gets fewer resources and attention from the parents, and that may have an impact on their mental health.”

Children from families associated with the most socioeconomic advantage had the best mental health.

However, other studies have shown that having more siblings is associated with lower likelihood of divorce.

“This combination of results is not easily explained. We still have more to learn about the impact of siblings,” Downey said.

“This is particularly important now as the US and other countries have lower fertility rates. Understanding the consequences of growing up with fewer or no brothers and sisters is an increasingly important social issue.”