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Bigger families, bigger stress? -

A new study suggests that teens growing up in larger families in the US and China may face more challenges when it comes to coping with everyday stress and emotional ups and downs.

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A global pattern -

Doug Downey, lead author of the study and sociology professor at Ohio State, found it striking that the same pattern appeared in both the US and China, highlighting a shared link between sibling count and adolescent mental health.

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A global pattern -

The study included data from over 9,400 eighth graders in China, collected through the China Education Panel Study, and more than 9,100 American eighth graders from the Early Childhood Longitudinal Study, offering a broad cross-cultural perspective.

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Unexpected findings -

“Our results were not what we expected,” said Downey. While other studies suggest that having more siblings can have positive effects, this study reveals a surprising connection between more siblings and poorer mental health.

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The sibling-free advantage -

In China, teens with no siblings reported the best mental health, according to the study.

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The sibling-free advantage -

In the US, teens with no siblings or just one sibling showed similar mental health outcomes, confirming that small family sizes can indeed positively impact adolescent well-being.

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The One-Child Policy effect -

As expected due to China’s One-Child Policy, about 34% of Chinese children are only children, significantly higher than the 12.6% of American kids, reflecting the different family structures in the two countries.

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A deeper look -

In both China and the US, researchers surveyed students around 14 years old about their mental health, though the questions varied between the two countries, allowing for a tailored analysis.

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Why more siblings might mean less support -

Downey links the findings to “resource dilution”—the idea that parental attention is like a pie. With one child, they get the whole thing, but with more kids, that pie is sliced thinner, leaving each with less.

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The logic behind resource dilution -

Downey explains that it’s simple math: more siblings mean less individual attention and fewer resources from parents, which can take a toll on a child’s mental health.

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Real talk: a mom’s take on resource dilution -

Tané Ruffin, a mom of six, shared that her 16-year-old and 12-year-old both agreed that resource dilution is a regular experience in their family, echoing the study’s findings about the challenges of growing up in larger households.

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Waiting their turn -

Ruffin’s kids confirmed the study hits home. One shared that she often holds back personal issues if mom’s already stressed with another sibling, which is a perfect example of how big families can stretch emotional airtime thin.

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Confidence vs. mental health -

When asked how her teens might score on the study’s mental health questions, Ruffin guessed they’d rate themselves lower, but she questioned the measures themselves, suggesting they reflect confidence more than true mental wellbeing.

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Sibling rivalry for attention -

Samantha Quigneaux, the national director of family therapy services at Newport Healthcare, notes that with more children comes more competition for parental time. 

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Sibling rivalry for attention -

When attention feels inconsistent or lacking, kids may feel neglected, which is a potential trigger for mental health struggles.

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Not all kids need the spotlight to shine -

Quigneaux adds that not every child fits the trend; some kids thrive just fine without constant parental attention, showing that individual temperament also plays a big role in mental well-being.

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Close in age, not in needs -

Psychologist Jeff Gardere points out that siblings close in age may still have very different emotional needs, but parents often treat them the same, overlooking those unique differences.

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Sibling relationships -

While the study links more siblings with lower teen mental health, it doesn’t explore how sibling relationships actually play out. A loving bond could make all the difference!

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Sibling relationships -

Downey notes that strong sibling bonds can actually boost mental health, reminding us that it’s not just the number of siblings—it’s the quality of the relationship that counts.

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Money, mental health, and family size -

Another factor at play? Teens with better mental health often came from wealthier families, suggesting that socioeconomic advantages might cushion the challenges of growing up with more siblings.

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Fewer kids, more cushion -

In both countries, smaller families tended to be wealthier. In the US, that meant one or two kids; in China, it usually meant just one, adding another layer to why these children reported better mental health.

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Norway breaks the mold -

Not all research agrees. A 2016 study from Norway, reported by The Guardian, found that kids from larger families actually had better mental health, suggesting culture and context make a big difference.

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More siblings, more friendships? -

Downey’s earlier research also showed that kids with more siblings often had stronger friendships at school. This suggests that the link between sibling count and mental health can vary, depending on social connections.

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Training for marriage? -

Kids from bigger families might be less likely to divorce later in life, possibly because growing up with siblings gives them early practice in managing close, sometimes tricky relationships.

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Sibling struggles today, gratitude tomorrow -

Geremy Keeton of Focus on the Family says teens may not see the perks of big families until later in life. “One study is just that—one study,” he noted, urging people to view it as just one piece of a larger puzzle.

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Still growing -

Downey emphasized that because the study focused on teens, the lasting impact of siblings on mental health is still “an open question” for future research.

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From sibling bickering to lifelong support -

Downey shared a personal note: growing up with two older brothers was challenging at times, but he now considers them great friends. “Fortunately,” he added, “no one struggled with mental health.”

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Understanding future family dynamics -

With families shrinking and only-child households on the rise, understanding how sibling count shapes our mental health isn’t just academic; it’s a growing social question that could define the next generation’s emotional well-being.

Sources: (The Guardian) (Ohio State News) (WORLD) (Deseret News)

See also: The world's happiest countries in 2025 

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