Sibling Influences on Childhood Development

To summarize the main points concerning sibling influence: 1. That siblings play a causal role in the development of aggressive behavior, in children's style of conflict behavior and in cooperative fantasy play is strongly suggested by recent research. 2. Marked problems in the sibling relationship are indicative of other problems, but a causal role for siblings is not established, other than for aggressive behavior. 3. Family factors are closely involved in the quality of sibling relationships--and thus in sibling influence, namely differential parental behavior, and the emotional climate of the family. That is, it is important not to consider the sibling relationship in isolation from other family relationships. 4. Studies of families under stress indicate heightened importance of these family factors. 5. It is likely, but not yet established, that later-born siblings are influenced by first-born in socio-cognitive development and gender identity. 6. Finally it should be noted that an important theme in current research on siblings is a concern with the question of why siblings develop to be so different from one another. It has been shown that the major source of environmental influence on the development of individual differences is within-family rather than between-family differences in experience (Plomin & Daniels, 1987). The different experiences each sibling may have within their relationship is one potential source of such differential environmental influence. Thus documenting the influence of siblings upon each other takes on added significance: By clarifying the extent and nature of this influence we will gain not only useful clinical information but illumination on a developmental principle of very general significance.