What are sibling relationships?

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Sibling relationships have been the object of increasingly detailed theoretical analysis and scientific investigation since the 1970’s. Such relationships show both change and stability over the life span. They are characterized by both rivalries and helpfulness, with helpfulness predominating.
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Sibling relationships grow out of interactions among children within a family. Such interactions occur on many levels and involve behaviors as well as the emotions and cognitions that accompany them. Sibling relationships begin at the time the first child becomes aware that a brother or sister has been added to the family and often continue into old age, ceasing only on the death of a sibling. Because they often last from early childhood to old age, sibling relationships are frequently the longest-lasting relationships in an individual’s life. Siblings’ relationships differ from those among friends in that they are not voluntary, cannot be terminated at will, and—during childhood—are daily and intimate in nature.

Prior to the 1970s, research concerning children’s development within families tended to stress parental influences on children’s behavior. By the 1970s, however, developmental psychologists had discovered that they needed more elaborate theoretical explanations to account for the variety of child behavior seen in their studies. In 1968, Richard Bell reviewed the existing literature and concluded that parents influence children and children also influence parents. This has been called a pattern of bidirectional influences.

As developmental researchers came to accept the bidirectional influences view, other theorists soon broadened perspectives on family dynamics. Family systems theory was articulated by writers such as psychiatrist and family therapist Salvador Minuchin in his 1974 book Families and Family Therapy. In this view, the behaviors and roles of all members of a family are interdependent, each influencing the others. Relationships frequently became researchers’ fundamental units of analysis, with all relationships seen as having the potential to influence one another and the entire family system. An ongoing rivalry between two brothers, for example, has the potential to erode the quality of their parents’ relationship. In the 1980s and 1990s, systems-oriented researchers incorporated into their understanding of sibling relationships additional variables, including social class, culture, genetic factors, child temperament, and individuals’ levels of social cognition(the ability to think and reason about interactions among people). Researchers also began to consider the relevance of ideas proposed by British psychiatrist John Bowlby in his three-volume work Attachment and Loss (1969–80). Bowlby’s attachment theory, which suggested that humans are biologically predisposed to form early social relationships, reinforced the notion that relationships develop early and are important in the subsequent development of the individual. At an early age, infants can become emotionally attached to familiar persons, including siblings.

The history of scientific attempts to understand sibling relationships, then, has been characterized by increasing appreciation for the complexity of such relationships and the diversity of contexts in which siblings learn to relate to one another. This complexity has created numerous methodological challenges for researchers.

Methodological Issues

Disparities among families with regard to number of children and spacing between children complicate investigators’ attempts to discover general principles that describe all sibling relationships. In addition, children’s gender is a variable that could influence relationships between siblings, and gender mix, too, varies across families. Birth order—being an oldest or youngest child in the family, for example—also may influence children’s interactions with brothers and sisters.

With so many variables operating and so much diversity possible across families, researchers have tended either to do relatively straightforward descriptive studies or to restrict their investigations to a subset of all possible family types. Early research attempted to assess the impact of global factors such as birth order, family size, or gender on variables such as personality or intelligence. As family systems theory began to influence research, however, investigators began studying relationships among siblings and the various forces to which these relationships respond. Studies carried out in the systems theory framework have generally limited their scope to a particular family type, such as two-child families with children under the age of five.

Even with such necessary limitations, however, investigators still have to consider several other methodological issues. They must decide whether they will get information through interviews, questionnaires, or direct observation of sibling interactions. If using an interview or questionnaire, they must decide whether to question parents, children, or both. If observations are to be done, should they be done in a laboratory or in participants’ homes? Another consideration is the type of siblings who will be studied. It has been common practice to study full siblings who share the same mother and father. However, half siblings, stepsiblings, and adoptive siblings may also be of interest, and researchers must decide whether to include them in their studies as well.

Psychologist and researcher Victor Cicirelli, in his 1995 book Sibling Relationships Across the Life Span, argued that sibling relationships must be studied longitudinally. Because sibling relationships can last a lifetime, it is valuable to know how they both change and remain the same over the entire life span. Only by studying such relationships over the long term can researchers develop an integrated, coherent body of knowledge about siblings’ lifelong relationships.


As infants and children grow, they change. The same can be said of childhood sibling relationships, for both members of any particular sibling pair are changing as individuals as their relationship grows. Research on the development of sibling interactions during childhood has been limited, but based on available information, some general observations can be reported.

Infants often do become emotionally attached to a sibling, just as they do to their mothers, fathers, and other caregivers. When the sibling relationship is positive and supportive, a secure attachment is likely to develop. Secure attachments during infancy predict healthy patterns of exploration as children get older, as well as successful adjustment to school and social situations.

Older children, being cognitively and physically more advanced than their younger brothers or sisters, tend to be leaders in sibling interactions. Younger siblings often imitate older brothers or sisters. Older children frequently act as linguistic interpreters as younger siblings learn to talk. As both siblings grow, the younger child becomes increasingly capable of actively participating in mutual activities; simultaneously, the older child may show increasing interest in the relationship.

An older sibling attends school and begins relating to peers earlier than a younger brother or sister, who may seek the advice of the older child when starting school. From the preschool period to school age, sibling pairs tend to remain fairly stable with regard to the proportions of positive and negative behaviors they exhibit. As children get older, they typically experience less adult supervision, which may pose a risk for sibling pairs with a predominantly negative relationship.

An observational study of the development of early sibling relationships published in 1982 illustrates the influence of family systems thinking on research. Judy Dunn and Carol Kendrick observed the development of sibling relationships for the first fourteen months after families had a second child. Older siblings were one and a half to three and a half years old when the new baby arrived. Dunn and Kendrick visited families in their homes several times and found that a majority of firstborns became more demanding and more likely to engage in naughty behavior in the weeks immediately following the younger child’s birth. Crying, clinging, and jealousy increased. Despite the negative reactions, however, most older siblings also reacted positively to the new child, cuddling the baby, helping take care of it, and showing concern when it cried. They also showed gains in taking care of their own needs independently. Siblings were especially likely to develop a close relationship with one another if, when speaking to the older child, mothers referred to the baby as an individual with interests, needs, and preferences. This finding is in keeping with family systems theorists’ belief that relationships within a family are interdependent.


The course of sibling relationship development during adolescence is less well understood than is the case for younger children. There is some evidence that the intensity of sibling relationships—for both positive and negative elements—may peak during early adolescence. Thereafter, power tends to become increasingly equivalent, and there is less tendency and less need for the older sibling to nurture the younger one. Conflict tends to be greater for siblings who are closer in age. Generally, same-sex siblings remain closer during this stage of life than do brother-sister pairs. Middle-aged siblings report recalling a drop in sharing and understanding during adolescence, followed by a resurgence of those characteristics during adulthood.


Little research on adult sibling relationships was done before the 1980s. That done thereafter tended to be largely descriptive or normative in nature. Cicirelli contends that this has occurred in part because researchers studying adulthood have worked in isolation from those studying childhood and adolescence.

Existing investigations suggest that affection characterizes most adult sibling relationships and that feelings of closeness may increase as siblings age. This may be particularly true for sisters. Relationships among adult siblings tend to be similar to friendships and often involve family celebrations or recreational activities. Elderly siblings often discuss family issues and reminisce.

Negative feelings between adult siblings are also reported, but overt hostility is rare. Affectionate feelings among siblings appear to be somewhat lessened in adults who spent part of their childhoods in a blended family (that is, a new family created by the remarriage of a parent). The few adult siblings—probably less than 11 percent—who have relatively little contact with one another have not been systematically studied.

Rivalry and Helpfulness

Both rivalry and helpfulness characterize sibling relationships across the entire life span. Joan Newman reviewed the literature on these features of siblings’ interactions in 1994 and suggested that conflict between siblings may be inevitable, owing to maturational discrepancies in social cognition between children of differing ages who are involved in an intense, complex, daily relationship. In part, the complexity of such relationships derives from their having both egalitarian qualities and inherent inequities (such as when one sibling is old enough to drive and the other is not). Newman points out that cognitively immature youngsters could hardly be expected to negotiate such relationships without feelings of competition, jealousy, or frustration.

Questionnaire and interview studies of older children and adults reveal widespread memories of competition, arguing, and verbal aggression in childhood sibling relationships. Memories of physical aggression are rare. Observational studies suggest that, although children show negativity in interactions with siblings more often than with peers or parents, negativity is not the predominant mode of relating.

Observational studies by Gene Brody and colleagues in 1982 and 1984 showed that eight- to ten-year-olds who were playing with a younger sibling tended to adopt cooperative but unequal roles (such as teacher and pupil). As children got older, there was some tendency for girls to play with a younger sibling more so than boys, perhaps because girls engage in more nurturant play activities and boys engage in more competitive physical activities.

Different studies have reported different proportions of positivity and negativity in sibling relationships. In part, the inconsistencies may be due to the methods used. Newman points out that parents’ reports may overemphasize rivalries while direct observations of children reveal relatively placid interactions. Children often report a mixture of feelings and attitudes. Further, because sibling relationships themselves often embody considerable variability, researchers can expect fluctuations in their findings.


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Brody, Gene H. “Sibling Relationship Quality: Its Causes and Consequences.” Annual Review of Psychology 49 (1998): 1–24. Print.

Brody, Gene H., ed. Sibling Relationships: Their Causes and Consequences. Norwood: Ablex, 1996. Print.

Cicirelli, Victor G. Sibling Relationships Across the Life Span. New York: Plenum, 1995. Print.

Diderich, Monique. Sibling Relationships in Step-Families: A Sociological Study. Lewiston: Edwin Mellen, 2008. Print.

Dunn, Judy. From One Child to Two. New York: Fawcett Columbine, 1995. Print.

Dunn, Judy, and Carol Kendrick. Siblings: Love, Envy, and Understanding. Cambridge: Harvard UP, 1982. Print.

Feinberg, Mark E., Anna R. Solmeyer, and Susan M. McHale. "The Third Rail of Family Systems: Sibling Relationships, Mental and Behavioral Health, and Preventive Intervention in Childhood and Adolescence." Clinical Child and Family Psychology Review 15.1 (2012): 43–57. Print.

Kluger, Jeffrey. The Sibling Effect: What the Bonds Among Brothers and Sisters Reveal About Us. New York: Riverhead, 2011. Print.

Milevsky, Avidan. Sibling Relationships in Childhood and Adolescence: Predictors and Outcomes. New York: Columbia UP, 2011. Print.

Newman, Joan. “Conflict and Friendship in Sibling Relationships: A Review.” Child Study Journal 24.2 (1994): 119–52. Print.