The Family & Parenting Institute said services should see children as part of a family, not just as lone individuals, following a Stirling University study, which found the way birth order and age affects family relationships is not fixed.
"Family policy has so far concentrated on the parent-child relationship, but it should bear in mind the positive and negative influences siblings have on each other," said a spokeswoman for the charity.
Mary MacLeod, chief executive of the institute, added: "Our brothers and sisters are for life and our relationship with them is a powerful mixture of love, rivalry, support, resentment and protectiveness."
"We have understood this in fiction and in clinical practice but there has been little research on the role of brothers and sisters in child development.
"We need to know more about how to support these relationships and how to help when they are troubled."
- www.cypnow.co.uk/doc.
