A parents' guide to minimising sibling rivalry

For the second time in a weekend, Cindy found herself banishing her two daughters to different corners of their home. She wondered where she had gone wrong as a mother - the girls' squabbles, screaming and general nastiness had escalated into physical slapping and scratching.

"It was a classic case of sibling rivalry, but I thought that only happened to babies and toddlers," she says. "What is so upsetting is that my girls aren't little any more - they're 13 and 16. They used to be such good friends, but instead of sharing clothes and secrets, all they do now is fight. Our house is like a war zone."

Most people, like Cindy, think of sibling rivalry as something that happens when children are small, but experts say it can happen at any age, and the teen years can be particularly difficult. Feelings of competition, inferiority, jealousy or simple personality differences can lead to disharmony at home.

"Every family has sibling rivalry to some extent," says Dr John Shanahan, a developmental psychologist at HK Central Health. "Factors such as the number of children and their ages really have an impact. For instance, there is the three-year-old who wants to poke, pinch or hurt the new baby; the eight-year-old who wants to wear make-up like her 14-year-old sister, or the 16-year-old twins who fight each other on the rugby pitch."

Although Shanahan mostly encounters sibling rivalry in younger children, he says conflict in teen years is generally due to feelings of inferiority, where one sibling seems better at everything: exams, sports and dealing with parents and peers.

Parenting coach Katherine Sellery agrees. Left unchecked, she says, feelings of inferiority can damage a relationship beyond repair. Many children have insecurities and these can be exacerbated when a child is not good at something but their sibling excels at it.