Bullying in the family: sibling bullying.

Sibling relationships have a substantial and lasting effect on children's development. Many siblings experience some occasional conflict, however, up to 40% are exposed to sibling bullying every week, a repeated and harmful form of intrafamilial aggression. We review evidence on the precursors, factors relating to peer bullying, and mental health consequences of sibling bullying. Parenting quality and behaviour are the intrafamilial factors most strongly associated with bullying between siblings. Sibling bullying increases the risk of being involved in peer bullying, and is independently associated with concurrent and early adult emotional problems, including distress, depression, and self-harm. The effects appear to be cumulative, with those children bullied by both siblings and peers having highly increased emotional problems compared with those bullied by siblings or peers only, probably because they have no safe place to escape from bullying. The link between sibling and peer bullying suggests interventions need to start at home. Health professionals should ask about sibling bullying and interventions are needed for families to prevent and reduce the health burden associated with sibling bullying.