In the context of the existing research on families, sibling violence is a less explored area. However, it has seemingly received more attention recently, and it can assume a relevant role in understanding the maladaptive behavior of youngsters and bullying. Additionally, adolescents involved in bullying and self-esteem are associated with disruptive violence inside the family context. This study's sample consisted of 286 students, aged between 12 and 17 years, from both sexes. This study intends to explore the association between sibling violence and bullying behavior in peers and the mediator effect of self-esteem. The measures for data collection were a demographic questionnaire, the Social Exclusion and School Violence Questionnaire, The Revised Conflict Tactics Scales (Portuguese version for siblings), and the Rosenberg Self-Esteem Scale. The results show a negative effect between negotiation in the sibling relationship (victimization) and social exclusion and verbal aggression related to bullying behavior. Self-esteem represents a total and negative mediator in this connection. Our results also show a variety of indirect outcomes amongst the negotiation dimension, psychological aggression and injury between siblings, and the social exclusion and verbal aggression dimensions (on the aggression and victimization scales). The results will be discussed according to the attachment theory but considering the importance of affective bonds with siblings as a predisposing factor to an adaptive development course.
Keywords: aggressors; bullying; self-esteem; sibling violence; victims.