#Birthorder

A wave of therapists are reporting a striking pattern in their sessions: the oldest children in families tend to surface topics tied to perfectionism, relentless self-criticism, and imposter syndrome more often than their younger siblings. The latest research exploration into birth order suggests these themes may be less about fixed personality traits and more about family dynamics, parental expectations, and cultural context. The lead from a prominent media outlet highlights what therapists are hearing most from oldest siblings, painting a portrait that resonates with many Thai families where elder children often shoulder early responsibilities and model behavior for younger siblings. While the research findings are nuanced and culturally contingent, they raise urgent questions for parents, teachers, and clinicians about how best to support first-borns without feeding a cycle of burnout or self-doubt.

The long-standing rivalry between siblings has taken a new turn as recent research shines a spotlight on a surprising “villain” within Thai and global families—the older brother. A large-scale study from the University of Warwick suggests that birth order does matter, with older brothers more likely to become the family aggressors, especially when it comes to bullying their younger siblings. This revelation not only disrupts traditional assumptions about sibling dynamics but also raises important questions about long-term well-being, family culture, and childhood development in Thailand.

New research is reshaping how Thai families think about sibling dynamics. A large-scale study from the University of Warwick indicates that birth order matters more than many thought, with older brothers more likely to be the aggressors toward younger siblings. The finding challenges long-held assumptions about family harmony and raises important questions for Thai childhood development, education, and mental health.

Sibling rivalry is a universal theme, but its expressions are deeply shaped by culture. In Thailand, the elder son often carries traditional responsibilities, including guidance of younger siblings and care for aging parents. These expectations can influence behavior and emotional dynamics at home. The latest study adds nuance to this picture, suggesting that the eldest brother’s role can include a troubling tendency toward bullying, especially in larger families.

New research is redefining how birth order—being firstborn, middle, youngest, or an only child—affects health, not just personality. For Thai families, these findings matter as family structures shift, parental roles evolve, and conversations about mental health gain prominence. The debate in Thai households about elder siblings’ maturity or middle-child dynamics now sits alongside rigorous science about childhood immune development, anxiety and depression risk, and obesity.

Experts say birth order effects are complex and layered. Health insights consider personality, coping strategies, and stress management shaped by position in the family. A 2024 Epic Research study highlights notable trends: firstborns show higher rates of anxiety and depression compared with their younger siblings, while only children and last-borns appear more prone to childhood obesity. Meanwhile, middle and younger children may experience stronger immune responses, a pattern linked to early-life exposure to germs and the so-called hygiene hypothesis. These findings hold potential relevance for Thai parents navigating smaller family sizes and evolving mental health awareness.

A wave of new research is shedding light on the intriguing ways that your birth order—whether you’re a firstborn, middle child, youngest, or only child—can impact not just your personality, but also your risks for certain mental and physical health conditions. The longstanding folk wisdom about eldest siblings being responsible, middle children overlooked, and youngest siblings more carefree has some scientific roots—but the picture is far more complex, with direct relevance for families in Thailand and around the world.