THURSDAY, Feb. 14, 2019 (HealthDay News) -- If you think that sibling rivalry can border on brutality at times, you won't be surprised by new research from British scientists.
They found that children are more likely to be bullied by a sibling if they have more than one, and firstborn children and older brothers are most likely to bully siblings, a new study finds.
"Sibling bullying is the most frequent form of family violence, and it is often seen as a normal part of growing up by parents and health professionals, but there is increasing evidence that it can have long-term consequences, like increased loneliness, delinquency and mental health problems," said lead study author Dieter Wolke, from the University of Warwick in England.
He and his team analyzed data from more than 6,800 British children born in 1991 and 1992 to assess bullying when the children were aged 5 and 12.
Bullying was defined as psychological (saying nasty or hurtful things), physical (hitting, kicking or pushing) or emotional (ignoring a sibling, telling lies or spreading false rumors).
About 28 percent of the children were involved in sibling bullying, and psychological abuse was the most common form. Most of those children bullied and were bullied, according to the study published online Feb. 14 in the journal Developmental Psychology.
Family structure and gender were the strongest predictors of sibling bullying by age 12.
"Bullying was more likely to occur in families with three or more children, and the eldest child or older brothers were more often the bullies. Female children and younger children were more often targeted," said study co-author Slava Dantchev, from the University of Warwick.
Bullying is more likely to occur in families with more children because resources such as parental affection/attention and material goods are more limited, the researchers explained.
"Despite our cultural differences, humans are still very biologically driven. A firstborn child will have their resources halved with the birth of a sibling, and even more so as more siblings are added to the family," Wolke said in a journal news release.
"This causes siblings to fight for those limited resources through dominance," he explained.
Wolke noted that sibling bullying "does not discriminate. It occurs in wealthy families just as much as lower-income families and it occurs in single-parent households just as much as two-parent households."
It's "important for parents to realize and understand that resource loss can affect an older child," Wolke said.
"It is a good idea for parents to manage this from the beginning by spending quality time with their firstborn or older children, and by involving them in caring for younger siblings," he suggested.
The American Academy of Pediatrics has more on bullying.
SOURCE: Developmental Psychology, news release, Feb. 14, 2019