Having a sister makes you healthier and happier -- scientifically; Here's how

Turns out, ‘ sisters before misters ’ is a science-backed proverb after all! Cause the one you fight for the wardrobe space with, the one you share your prized prom dresses and well-guarded make-up hacks with, and the one you can give up the last slice of pizza and the last scoop of ice-cream for – is the secret sauce to your happiness!

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Don’t worry, we’ll explain!

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Picture this: a living room, two sisters on the couch, swapping secrets and giggling. Now imagine that this everyday moment has been meticulously studied—and guess what? That bond does more than fill your Instagram feed—it fuels your mental wellness and boosts your happiness, too!



Sisters: The Serotonin Superheroes

Imagine a lab where researchers don scrubs—not for test tubes, but to decode sisterly power. That’s exactly what a team led by Prof. Tony Cassidy from Ulster and Liz Wright from De Montfort did almost two decades ago. In 2009, Prof. Tony Cassidy (Ulster) and Dr. Liz Wright (De Montfort) surveyed 571 young adults (17–25) and found a clear pattern: those with at least one sister reported higher happiness, stronger optimism, better emotional coping, and richer social support than those with only brothers or no siblings.

As reported by The Telegraph, Professor Tony Cassidy, from the University of Ulster, who carried out the study with researchers from De Montfort University in Leicester, said that having a sister helped to promote good mental health.


He said: "Sisters appear to encourage more open communication and cohesion in families. However, brothers seem to have the alternative effect. Emotional expression is fundamental to good psychological health and having sisters promotes this in families."

According to the findings, girls who had sisters also tended to be more independent and keen on achievement. Notably, the effects were stronger among children from broken homes, suggesting that sisters might lean on each other more for support when their parents divorce.

Prof Cassidy added that the lowest scores were among boys who had only brothers.

As per him, "It could be that boys have a natural tendency not to talk about things. With boys together, it is about a conspiracy of silence not to talk. Girls tend to break that down."

Only children tended to score in the middle range for happiness and optimism.

Liz Wright, the co-author of the study, said: "With only children we found that they had lots of strong communication outside of the home. It appears that they have as much social support as those with siblings, but it does not come from within the family."


Sisterhood : The Secret Superglue


Here’s the scientific truth. Sibling warmth serves as a powerful social cushion, especially as a stress-reliever amidst familial crises. In fact, NPR confirms that any warm sibling bond in early adulthood predicts lower anxiety, depression, and loneliness by midlife. Social support—whether from family or friends—is linked to better emotional regulation, lower cortisol, stronger immunity, and reduced risk of depression, heart disease, and mortality. Sisters? They’ve just mastered the art of emotional tuning more quickly.


Here’s how.

They’re built-in therapists

A 2010 BYU study revealed sisters “protected adolescents from feeling lonely, unloved, guilty, self-conscious or fearful”—not just older sisters, but little ones too . They serve as confidantes, sounding boards, and emotional support—like personal counselors with no waiting list.


Communication champions

Females tend to rehash social interactions more. In trust-game brain scans, women’s caudate (reward-processing) activity stays switched on long after decisions, suggesting they value connection continuity more deeply. That nuance, repeated daily with a sister, can morph into emotional fluency.


Confidence and independence boosters

Cassidy and Wright noted that daughters with sisters—especially in divorced households—scored higher on ambition and self-determination. That same effect was observed in boys, who gained better communication and conflict-resolution skills from growing up with sisters.


What about brothers?

Before you go all grumpy over the lack of validation for having brothers, here’s the deal. The messaging here isn’t at all about ‘brothers are bad’; rather, it reiterates that sisters uniquely foster communication and emotional openness. Brother-only families tend to be quieter; daughters break down emotional walls.


Deriving from the study, Cassidy and Wright pinpointed the why: sisters cultivate open emotional dialogue. While brothers may default to a “conspiracy of silence,” sisters often break it, encouraging honest, heartfelt conversation, which is a crucial ingredient for psychological well-being. The effect is amplified in single-parent or divorcing households. A 2009 study found family units with at least one sister—especially daughters—showed less distress when parents split, pointing to sisterly support as an emotional buffer.

As Cassidy put it, "emotional expression is fundamental to good psychological health and having sisters promotes this in families."

In contrast, the study found boys raised only with brothers scored lowest on emotional and coping measures, suggestive of emotional suppression, not resilience.

Moreover, only children usually fall between siblings and large brother-packed families in well-being and often compensate by forging strong external friendships.


The bottom line:

The key takeaway from the research is clear: Sisters are more than just siblings; they are each other’s emotional anchors. Their emotional chatters spark real conversations, teach emotional literacy, and embed resilience. Their ‘yapping’ catalyzes emotional intelligence, builds compassion, and boosts empathy. They’re the built-in (and free of cost) therapists, cheerleaders, confidence boosters, and resilience architects, bundled in siblinghood. They teach you how to feel, how to cope, and how to face life’s challenges with grit and laughter. In the ecosystem of mental health, sister-like bonds are the unsung heroes of happiness.


They’re not just playmates or roomies – they’re your emotional support cushions in human form.

So, if you have a sister, treasure her. If not, identify your “chosen sister”—a close friend, a mentor, or a cousin—someone who offers that same space for heartfelt connection and emotional check-ins. Cultivate that sisterly warmth with someone who holds your heart—it might just be the secret to lasting happiness.