From Childhood, 

Howe, N., Paine, A. L., Ross, H. S., & Recchia, H. (2022). Sibling relations in early and middle childhood. The Wiley‐Blackwell handbook of childhood social development, 443-458.

to Adolescence,

Rogers, C. R., Guyer, A. E., Nishina, A., & Conger, K. J. (2018). Developmental change in sibling support and school commitment across adolescence. Journal of Research on Adolescence, 28, 858–874. https://doi.org/10.1111/jora.12370

Young adulthood,

Jensen, A. C., Whiteman, S. D., & Fingerman, K. L. (2018). “Can’t live with or without them:” Transitions and young adults’ perceptions of sibling relationships. Journal of Family Psychology, 32(3), 385.

Midlife-older age,

Gilligan, M., Stocker, C. M., & Jewsbury Conger, K. (2020). Sibling relationships in adulthood: Research findings and new frontiers. Journal of Family Theory & Review, 12(3), 305-320.

and Later life.

Stocker, C. M., Gilligan, M., Klopack, E. T., Conger, K. J., Lanthier, R. P., Neppl, T. K., ... & Wickrama, K. A. S. (2020). Sibling relationships in older adulthood: Links with loneliness and well-being. Journal of Family Psychology, 34(2), 175-185.

Conflict in sibling relationships is normative, but may seem problematic to many parents. Much work has examined sibling problem solving skills, and shows promising trends that siblings who may have higher than normal conflict often decline in conflict over time. 

Howe, N., Fiorentino, L. M., & Gariépy, N. (2003). Sibling conflict in middle childhood: Influence of maternal context and mother-sibling interaction over four years. Merrill-Palmer Quarterly (1982-), 183-208. https://www.jstor.org/stable/23096227 

Karavasilis Karos, L., Howe, N., & Aquan‐Assee, J. (2007). Reciprocal and complementary sibling interactions, relationship quality and socio‐emotional problem solving. Infant and Child Development: An International Journal of Research and Practice, 16(6), 577-596. https://doi.org/10.1002/icd.492

Tucker, C. J., Cox, G., Sharp, E. H., van Gundy, K. T., Rebellon, C., & Stracuzzi, N. F. (2013). Sibling Proactive and Reactive Aggression in Adolescence. Journal of Family Violence, 28(3), 299–310. https://doi.org/10.1007/s10896-012-9483-8 

Through sibling relationships may vary considerably by genetics and family structure, Sibling relationships continue to provide substantial influences on behavior above and beyond that seen by parents and friends.