0749 GMT November 22, 2019
The research, which was carried out by Oxford, Bristol, and Warwick universities, asked around 7,000 children aged 12 if they had experienced a sibling saying hurtful things, hitting, ignoring them or lying about them.
The questionnaire said, "This means when a brother or sister tries to upset you by saying nasty and hurtful things, or completely ignores you from their group of friends, hits, kicks, pushes or shoves you around, tells lies or makes up false rumors about you."
The children were followed up at 18 and asked about their mental health.
Those who had experienced such bullying were approximately twice as likely to experience depression, anxiety, and to self-harm than those who had not.
Lead author Dr Lucy Bowes, from the department of social policy and intervention at the University of Oxford, said, "We are not talking about the sort of teasing that often goes on within families, but incidents that occur several times a week, in which victims are ignored by their brothers or sisters, or are subjected to verbal or physical violence."
The researchers concluded that “being bullied by a sibling is a potential risk factor for depression and self-harm in early adulthood”. They suggest that interventions to address this should be designed and tested.