The Enduring Power of Sibling Relationships
For the majority of people, the longest human connection they will ever experience won't be with a spouse or childhood friend - it will be the bond shared with brothers and sisters. This relationship typically begins before we form friendships outside the family and usually long before we choose romantic partners. In the United Kingdom, approximately 80 percent of people have siblings, making this one of the most common yet frequently overlooked relationships in our lives.
The Science Behind Sibling Connections
Recent scientific research has begun to illuminate the profound impact sibling relationships have on our psychological wellbeing. A groundbreaking 2024 Finnish neural imaging study discovered that sisters exhibited more similar brain activity patterns than friends or acquaintances while watching films together. This fascinating finding provides scientific validation for that nebulous feeling of being on the same "wavelength" that many siblings report experiencing.
Further research published in the Journal of Family Psychology during 2024 revealed that a warm, supportive bond with a sibling during early adulthood correlates with significantly lower levels of anxiety and depression in midlife. Conversely, strained sibling relationships during this formative period predicted higher rates of psychological distress later in life. Another study published earlier this year demonstrated that a child's sense of security and wellbeing might be rooted not only in their attachment to parents but equally in their connection to siblings.
The Complex Reality of Sibling Dynamics
Despite the potential for profound joy and support, sibling relationships are rarely simple. These bonds can be fraught with jealousy, resentment, and long-standing rivalries that sometimes trace back to childhood slights. Cultural narratives from biblical stories to contemporary television dramas like "Succession" have explored the dramatic potential of these complex family dynamics.
Research estimates that approximately one in four people experience estrangement from a brother or sister at some point in their lives. High-profile examples like the reported tensions between Princes William and Harry or various celebrity family rifts illustrate just how painful navigating these relationships can become. Many others find themselves somewhere between extreme closeness and complete estrangement - maintaining cordial relationships through annual gatherings but little meaningful connection beyond that.
Examining Sibling Relationships with Nuance
Broadcaster and writer Catherine Carr, host of the "Relatively" podcast, has made sibling relationships her professional focus. Her new book, "Who's the Favourite?: The Loving, Messy Realities of Sibling Relationships," examines this particular form of kinship with unprecedented depth and nuance. Carr brings unique perspective to the subject as one of three sisters whose family circumstances created unusual dynamics.
When Carr was eleven, her parents separated, with her mother moving to a nearby town with a new partner and taking the youngest sister, while Carr and her older sister returned to the United Kingdom with their father. This division fundamentally altered their family unit, creating what Carr describes as a realignment of hierarchies. When both parents eventually remarried, two sets of step-siblings further complicated the family dynamic.
"I've always had to think more intentionally about building the sibling bond than people who grew up in the same house," Carr explains. "People who share a childhood home might - not in a way I would feel judgmental about - take their sibling relationships for granted. I couldn't take mine for granted. And so I've always been intentionally working to be close to my sisters, together as a three."
The Evolution of Sibling Roles
Carr notes that sibling relationships present unique challenges partly because "you don't choose them" and partly because our positions relative to siblings shift dramatically over time. "They don't start out in life as your peers," she observes. "You start out hierarchical: someone's above you, someone's below you, you're somewhere in the middle. And then, over time, you become horizontal peers."
The Journal of Family Psychology study identified age twenty-three as a significant turning point when sibling relationships typically become more emotionally stable. Once individuals reach adulthood, they begin to settle into parallel life trajectories where age gaps of a few years matter less significantly. "That doesn't really happen with other relationships," Carr adds, highlighting what makes sibling bonds uniquely dynamic.
Beyond Birth Order Stereotypes
Cultural assumptions about birth order continue to shape how we understand sibling relationships. Eldest children are frequently characterized as responsible high-achievers, with entire social media genres dedicated to analyzing the "eldest daughter" disposition. Middle children supposedly suffer from "middle child syndrome," perpetually overshadowed by their siblings. Youngest siblings are often viewed as pampered princes and princesses of the family.
Many of these cultural ideas trace back to the work of Alfred Adler, an early twentieth-century Austrian psychologist who was himself one of seven siblings. Adler characterized firstborns as "privileged, but also burdened by feelings of excessive responsibility" and "prone to score high on neuroticism." He viewed middle children as "jealous, insecure, outgoing and adaptable" while describing youngest siblings as "charming, outgoing, free spirited, manipulative, immature and open to taking risks."
In the 1990s, American psychologist Frank J. Sulloway developed "niche theory," suggesting that children adopt disparate roles or traits to differentiate themselves from siblings and maintain parental attention. According to this theory, if all children had similar personalities, they might not be "distinctive enough to pique their parents' interest," as Carr summarizes in her book.
Breaking Free from Childhood Roles
Carr emphasizes that family dynamics create unusual situations where we "get our sense of self from comparing ourselves to just a handful of other people." She notes, "These are ideas that are based on how you were when you were seven - there's no other relationship or situation where you would be using that as a benchmark."
If someone grows up being compared to a sibling labeled the "bright one," they might internalize a self-perception of being less intelligent. "Why are you comparing yourself to two people and getting a sense of your identity, then walking out into the world of eight billion people and thinking, 'I'm not as clever as Juliet!' Well, you're not as clever as Salman Rushdie, either. That doesn't mean you're not clever," Carr observes.
Her book isn't intended as a therapeutic manual or a sentimental celebration of sibling relationships. Rather, Carr suggests that allowing these connections to evolve over time - adapting to what siblings are like now rather than remaining fixed in childhood perceptions - represents one pathway toward healthier bonds. "You can start to think about changing the way that you're seen by the family by letting them see you more as you are in the world," she advises.
Carr recently experienced this evolution firsthand when her younger sister surprised her by taking charge and booking her into an Airbnb to focus on an impending work deadline. "You can sometimes be taken care of by others, you know," her sister told her, adding, "Just consider it payback for some of the other stuff." This moment represented a meaningful shift in their long-established dynamic.
As research continues to reveal the significant impact sibling relationships have on mental health and wellbeing throughout life, Carr's work offers valuable insights into nurturing these complex, lifelong bonds that shape who we become.
