Siblings and Their Lasting Impact

Source: Jacob Wackerhausen / istock

When we think about the relationships that shape us, we often default to discussing our parents. Decades of psychological research have explored the influence of parenting styles, attachment dynamics, and parental decision-making on child development. Yet, this parental focus often overshadows one critical relationship—that of siblings.

From a Bowen Family Systems Theory perspective, siblings form the bedrock of our social and emotional development. They are our first peers, and these relationships provide the framework for how we interact with the world. Whether we lean toward cooperation or competition, sensitivity or distance, or develop a leadership style versus a more passive role, much of it stems from the unique dynamics we experience with our brothers or sisters.

Bowen Family Systems Theory and Sibling Position

Bowen Family Systems Theory emphasizes the interconnectedness of family members, suggesting that a family's "emotional field" profoundly shapes individual functioning. Within this theory, sibling position plays a critical role. Bowen's concept of sibling position draws on the early work of researchers like Walter Toman, who explored patterns of personality traits based on birth order.

Toman's research indicates that firstborn children often take on leadership roles, displaying qualities such as responsibility, organization, and a desire to please authority figures. These traits are usually developed as older siblings are often expected to set examples for their younger siblings. Conversely, later-born children, like second or third children, may develop characteristics that contrast with their older siblings' characteristics.

Middle children, in particular, have a unique position in the sibling hierarchy. Toman described them as often feeling "sandwiched" between their elder and younger siblings, leading to distinct personality traits. They tend to be peacemakers, highly adaptable, and sensitive to the dynamics around them. Middle children often develop skills related to negotiation and compromise, as they navigate the varying expectations and roles established by their siblings. This adaptability can lead them to become more independent and resourceful. Additionally, they may exhibit traits of rebellion or nonconformity, as they strive to carve out their own identity in contrast to the established roles held by their elder siblings.

Another interesting aspect of Toman's research emphasizes that only children share characteristics with firstborns but often exhibit attention-seeking qualities, as they do not have siblings to compete with for parental attention. Overall, the birth order dynamics highlighted by Toman enrich the understanding of individual personalities and behaviors within the family system, showing how each sibling's position can influence their development and relationships.

Bowen noted that individuals often replicate these sibling roles in their adult relationships. For example, a firstborn sibling in a family may naturally take on leadership roles at work or in social settings, while the youngest might learn to be dependent or charming to elicit support. Importantly, the unique interaction between sibling roles and the family system shapes how these roles manifest—not every firstborn is the same, nor is every youngest child.

The Foundational Role of Sibling Relationships

The role of siblings goes far beyond childhood power struggles or alliances over who gets to control the TV remote. Siblings often serve as emotional mirrors. Through them, we learn how to manage conflict, express empathy, compete, collaborate, and reconcile. Unlike parent-child relationships, sibling interactions are horizontal rather than hierarchical, creating a space for children to practice interacting with equals.

Research has found that sibling relationships predict several adult outcomes, including well-being, social skills, and even mental health. For instance, a study by Whiteman, McHale, and Soli (2011) highlights that positive sibling relationships are associated with greater self-esteem and social competence in adulthood. Conversely, unresolved sibling conflict may lead to long-term difficulties in forming and maintaining other relationships.

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When siblings act as allies, they buffer the stress of difficult childhood experiences. Siblings often "co-parent" one another in family systems where parents are emotionally unavailable, creating informal caregiving roles that may later inform professions or partnerships. Yet, despite this profound influence, sibling relationships remain one of the most under-explored facets of developmental psychology.

A Research Gap Worth Bridging

The lack of research on siblings compared to parents is surprising, especially given the enduring nature of sibling bonds. Parent-child relationships often evolve to become less central in adulthood, but sibling ties frequently last a lifetime, even outliving marriages and friendships. Siblings are usually present for milestone moments, ranging from weddings to funerals, and their shared experiences form a unique repository of familial history.

Despite this, funding and research energy are disproportionately devoted to studying parents. Parent-focused studies dominate discussions about attachment, discipline, and emotional development, while sibling dynamics are often relegated to secondary status. This gap in research limits our understanding of family systems, preventing us from fully recognizing the formative impact of sibling relationships.

However, sibling research is catching up. Recent studies have explored how siblings influence career paths, cognitive development, and mental health outcomes. For example, research published in the journal Child Development by Buist and Vermande (2014) sheds light on how sibling warmth and conflict impact emotional regulation in children. Meanwhile, studies on sibling differentiation reveal how children within the same family often carve out unique identities to reduce competition and maintain individuality. These findings emphasize the need for greater attention to the longitudinal consequences of sibling dynamics.

What This Means for Families and Therapists

Understanding sibling dynamics can help families create healthier relationships among their children. Encouraging collaboration over competition and teaching conflict resolution early can set the stage for positive lifelong bonds. For therapists, acknowledging sibling relationships as a foundational family structure provides a more holistic lens when assessing a client's challenges. When clients reflect on themselves solely as someone's child, a significant part of their emotional landscape may remain unexplored.

By considering the influence of siblings alongside parental relationships, family therapists can develop richer narratives about how individuals view themselves and others. A sibling-focused perspective allows for deeper interventions and greater empathy, not just for what the client experienced but for how their earliest social training shaped the adult they are today.

Siblings are more than just people we share childhood homes or DNA with. They are co-authors of our personal stories, helping us prepare for the world beyond our family of origin. Yet, they remain an underappreciated influence in the psychological literature. As research advances, it's time to shine a light on the complex, formative world of sibling relationships and give siblings their rightful place at the table in conversations about human development.