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Sibling Relationships and Conflict Across Development

Roamers Therapy I November 2026

Our relationships with siblings provide a natural playground for developing some of our most important social and thinking skills, from language and humor to understanding right and wrong and how to behave toward others. From play to conflict, these relationships help set the tone for the relationship patterns that we carry into adulthood. Because sibling relationships are among the longest we have, their effects go beyond childhood and adolescence and can shape our quality of life into later adulthood and beyond. As our siblings help us become who we are, they can provide many things in life, from conflict and distress to support and a deep bond. 

Factors that influence sibling relationships and conflict

Siblings are active participants in family systems, where they both influence and are influenced by other family members. This means that while challenging sibling dynamics can cause distress within families, existing family distress can also contribute to negative sibling dynamics. 

Just as importantly, family dynamics are not isolated from broader social and cultural influences. How a family chooses to raise children, and the rules they set at home, can vary greatly because of cultural traditions and economic pressures. As children grow up and their social worlds expand, peers and other adults can also begin to affect siblings’ individual identity development and family dynamics. 

Common factors that tend to affect sibling dynamics include:

  • Child-related factors
    • Child’s temperament: differences in each sibling’s personality, including being sensitive, easily frustrated, patient, or outgoing
    • Social-cognitive development level: children’s developing capacities for understanding their and other people’s feelings and intentions, communication skills, emotion regulation, and more
    • Age difference: age gap between siblings, including effects through how much they have in common, whether they will play together, and more
  • Caregiver-child relationship related factors
  • Differential treatment: differences in how caregivers treat their children (giving one child more attention, praise, or privilege)
  • Level of caregivers’ intervention during conflict: how caregivers respond when siblings have a conflict, including taking sides, helping children resolve disagreements
  • Rules and expectations: household rules, boundaries, what is expected of children 
  • Parenting style: Differences in how caregivers raise and discipline their children, such as being more strict, protective, permissive, or supportive toward children. For example, both overly strict and aggressive styles and overly permissive environments can lead to more conflict between siblings through aggression being modeled to them or lack of routines or rules shaping children’s dynamic
  • Family and sociocultural factors
  • Quality of caregiver relationship: how caregivers get along and communicate, as well as handle conflict themselves
  • Caregiver mental health: caregivers’ individual mental well-being and struggles with stress, as well as how they engage in self-care and self-regulation
  • Family’s overall functioning: General atmosphere in the household and level of warmth, affection, tension, and conflict children get to experience; how well members communicate and cooperate together
  • Socioeconomic factors: life events and transitions such as financial difficulties, changing homes, as well as impact of the sociocultural environment in family  dynamics and rules, including access to resources and opportunities

Changing sibling dynamics and ways conflict may show up at different ages

Welcoming a new sibling

Welcoming a new sibling into a family is one of the most common changes children go through. While children tend to show both positive and negative reactions to this change, it can also be a major source of stress for caregivers and the older child. For example, the older child may show increased confrontation and aggression, become more clingy with caregivers, show greater frustration and anxiety when separated from caregivers, experience jealousy toward the newborn, and exhibit behavioral issues such as toileting problems, sleep issues, and more. This may be because the older child feels their safety is threatened, family stress increases due to caregiver exhaustion and disrupted routines, and older children feel pressure to become the “big child.”

While most children adapt to welcoming a new sibling within around four months, conflict may escalate again after the first year as the younger sibling starts to move around and becomes more curious and engaged with others. While older siblings may be able to assert themselves at certain ages, as the younger sibling grows older and becomes more physically active, they may also begin to respond, which can lead to conflicts involving aggression, teasing, and provoking each other.

Depending on the developmental age of the siblings, sources of their distress and their capacity to regulate and respond also evolve. This makes sibling conflict emerge in new and unique ways, as we discuss below.

Infancy

When siblings are younger, their distress due to the loss of exclusive caregiver attention, jealousy and confusion toward the newborn baby, and changes in family routines can show up more behaviorally through:

  • Increased crying and fussiness.
  • Clinginess and difficulty separating from caregivers.
  • Changes in feeding or sleeping patterns.
  • Increased irritability and difficulty self-soothing.
  • Distress when caregivers hold or attend to the newborn.

Toddlerhood (1-3 years old)

  • As the children grow and become more mobile during toddlerhood, reciprocal play, imitation, and early cooperation begin to develop between siblings. Still, challenges with impulse control and emotion regulation can create difficulties.
  • Limited perspective-taking and competition can lead to issues such as difficulty sharing toys.
  • Limited emotional regulation can manifest as hitting, pushing, and screaming.
  • Developmental differences (e.g., age gaps) can increase frustration with a toddler sibling.

Preschool Years (3-5 years)

  • Difficulty with negotiation can increase and may show up through protesting or arguing over play rules and leadership.
  • Jealousy and social comparison may emerge and show up as negative comments and exclusion from play.
  • Because emotional and verbal skills are still developing, frustration may continue to show up through tantrums and aggressive responses.
  • Still-developing cognitive skills, such as theory of mind, can make misunderstandings and miscommunications more likely, such as interpreting accidental actions by siblings as deliberate.

Middle Childhood (6-11 years)

  • As children grow older and their individual social circles expand, competition and a sense of differential treatment may increase.
  • Children’s experiences of differential treatment may show up as resentment or accusations of favoritism, as well as arguments about privileges and fairness.
  • Differences in academic achievement and individual social circles may lead to conflicts, manifesting as boasting or belittling each other.
  • With increased mobility and physical capacity, coercive interactions involving intimidation, retaliation, and submission may also emerge, and aggression can escalate into violent behavior.

Adolescence (12+ years)


As adolescence brings increased challenges around identity and autonomy, sibling conflict can also show up in unique ways.

  • Adolescent siblings may experience increased privacy and boundary violations, such as others entering their rooms or accessing their belongings, phones, or both.
  • Family members’ responses to an adolescent sibling’s identity differentiation may sometimes show up as criticism of their clothing, interests, or choice of friends.
  • Siblings who share similar social or school circles may experience increased social comparison and challenges around perceived differences in appearance, popularity, or achievements.
  • Age differences between siblings can create additional conflict over rules and privileges, such as arguments over unequal freedoms.
  • The influence of peers and the social environment on adolescents, along with an increased likelihood of risky behaviors such as smoking or substance use, can complicate existing challenges.
  • Older children may experience increased expectations to take on caregiving and household responsibilities. This can affect their perception of their younger sibling and see their relationships more of a duty and responsibility rather than playfulness, spontaneity, and emotional connection.
  • When an older sibling’s increased need for autonomy and privacy goes unaccommodated, this need may start showing up as increased distance and avoidance of the younger sibling, which can create further emotional ruptures in the relationship.

How can therapy help?

​​Therapists often start by understanding the nature of sibling conflict through appropriate assessment procedures, including interviewing caregivers and siblings, observing sibling dynamics through play or conversation, collaborating with other healthcare or school professionals, and using more structured assessment techniques such as questionnaires. Through these, therapists can try to establish:

  • The types of conflicts siblings engage in, consistent themes, and the severity of the events
  • The function or benefit the conflict may be serving in the dynamic (Are they ways of expressing frustration, resentment, or insecurity; gaining caregiver attention or reassurance; competing for parental affection; communicating personal boundaries and needs; or managing difficult emotions or something else?)
  • How caregivers and siblings have handled the conflict in the past.
  • General characteristics of the sibling dynamic, including how the older sibling initially received the younger sibling and how their relationship developed across different developmental stages.
  • Caregiver styles and the kinds of behaviors caregivers model, including caregivers’ interactions with each other and with their children.
  • Whether any siblings experience conflict in other relationships or areas of their lives.
  • Individual strengths and unique stressors experienced by different family members

Treatment and therapy options may depend on the level and type of treatment, including whether it targets one sibling, caregivers, the environment and family, or the broader setting, such as schools or neighborhoods. For example, individual interventions with any sibling may include helping children learn and role-play communication and conflict-resolution skills and improve emotional regulation so they feel more equipped in the sibling relationship and can navigate challenges more effectively. Family- or caregiver-level interventions may also target and improve interactions between members.

Similarly, specific methods used by therapists, such as play therapy or parent-child interaction therapy, or the attachment regulation and competency (ARC) framework, may offer different opportunities to prioritize the focus area, improve the bond between family members, and address sources of distress. For example, with therapy, using cooperative games between siblings or storytelling can help explore and address sibling conflict, especially for younger children. With ARC, attachment between caregivers and children can improve by strengthening caregiver attunement and emotional regulation and by developing children’s social and relational competencies.

Takeaways

  • Sibling relationships are a natural playground for us to develop important social and thinking skills and can shape relationship patterns and quality of life into adulthood.
  • Sibling dynamics can be pretty nuanced and influenced by child-related factors, caregiver-child relationships, overall family functioning, and broader sociocultural and socioeconomic influences.
  • Welcoming a new sibling can be a major source of stress, with older siblings experiencing complex emotions such as jealousy, anxiety, behavioral changes, and difficulties adapting to changes in family routines.
  • Sibling conflict is an expected part of growing up and evolves across developmental stages, although it can also escalate to more aggressive and dangerous behavior when children are left without support. It can show up as clinginess and difficulty sharing in early childhood, then shift to competition, boundary violations, privacy concerns, and autonomy struggles during adolescence.
  • Understanding sibling conflict requires assessing its patterns, underlying functions, family dynamics, caregiver responses, and the individual strengths and stressors of family members.
  • Therapy can help siblings develop communication, emotional regulation, and conflict-resolution skills while strengthening family interactions and attachment through approaches such as play therapy, parent-child interaction therapy, and the ARC framework.

References & further reading

  • Kramer, L., Howe, N., & Volling, B. L. (Eds.). (2026). Handbook of the psychology of sibling relationships: Advancing research and practice. Springer. https://doi.org/10.1007/978-3-032-21296-2 
  • Prinstein, M. J., Youngstrom, E. A., Mash, E. J., & Barkley, R. A. (Eds.). (2019). Treatment of disorders in childhood and adolescence (4th ed.). Guilford Press. 
  • Schroeder, C. S., & Smith-Boydston, J. M. (2020). Siblings and peers. In Assessment and treatment of childhood problems: A clinician’s guide (3rd ed.). The Guilford Press.
  • Edwards, R., Hadfield, L., Lucey, H., & Mauthner, M. (2006). Sibling identity and relationships: Sisters and brothers. Routledge. https://doi.org/10.4324/9780203448809 
  • Dirks, M. A., Persram, R., Recchia, H. E., & Howe, N. (2015). Sibling relationships as sources of risk and resilience in the development and maintenance of internalizing and externalizing problems during childhood and adolescence. Clinical Psychology Review, 42, 145–155. https://doi.org/10.1016/j.cpr.2015.07.003
  • Jensen, A. C., Killoren, S. E., Campione-Barr, N., Padilla, J., & Chen, B. (2022). Sibling Relationships in Adolescence and Young Adulthood In Multiple Contexts: A Critical review. Journal of Social and Personal Relationships, 40(2), 384–419. https://doi.org/10.1177/02654075221104188
  • Kramer, L. (2010). The Essential Ingredients of Successful Sibling Relationships: An Emerging Framework for Advancing Theory and practice. Child Development Perspectives, 4(2), 80–86. https://doi.org/10.1111/j.1750-8606.2010.00122.x
  • Tucker, C. J., & Finkelhor, D. (2015). The State of Interventions for Sibling Conflict and Aggression: A Systematic review. Trauma Violence & Abuse, 18(4), 396–406. https://doi.org/10.1177/1524838015622438
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