Siblings play a unique role in one another's lives that simulates the companionship of parents as well as the influence and assistance of friends.[1] Because siblings often grow up in the same household, they have a large amount of exposure to one another, like other members of the immediate family. However, though a sibling relationship can have both hierarchical and reciprocal elements,[2] this relationship tends to be more egalitarian and symmetrical than with family members of other generations. Furthermore, sibling relationships often reflect the overall condition of cohesiveness within a family.[3]
Siblings normally spend more time with each other during their childhood than they do with parents or anyone else; they trust and cherish each other, so betrayal by one sibling could cause problems for that person physically as well as mentally and emotionally. Sibling relationships are often the longest-lasting relationship in individuals' lives.[2][4]