Studying Siblings Within Family Systems: Theory, Methods, and Models

Sibling relationships are dynamic and complex relationships that develop and operate within the context of the family. Capturing this embeddedness of siblings in the family has long been a challenge for researchers as it requires the design of research questions, methods, and statistical modeling that respects the interdependent nature of family relationships. Family systems theory (FST) offers an excellent framework for conceptualizing these interdependencies, yet few researchers fully exploit the promise of this rich theory. FST can guide the study of how sibling subsystems affect, and are reciprocally affected by, other family subsystems, while considering developmental processes and ecological, ethnocultural, and socioeconomic contextual factors. In line with the sibling-informed theoretical framework presented in Chap. 2 of this volume (Kramer et al., Handbook of the Psychology of Sibling Relationships: Advancing Research and Theory. Springer Nature, 2026b), this chapter describes the theoretical tenets of FST that may optimally guide future research on sibling relationships. Additionally, this chapter will highlight the ways in which research questions can be articulated, and methodologies selected, that reflect FST principles. Finally, we address statistical modeling approaches that can capture the dynamic nature of sibling relationships and their effects on children’s development and well-being.