Sibling rivalry
（重定向自Sibling rivalry disorder）
Sibling rivalry is a type of competition or animosity among siblings, whether blood related or not.
Siblings generally spend more time together during childhood than they do with parents. The sibling bond is often complicated and is influenced by factors such as parental treatment, birth order, personality, and people and experiences outside the family. Sibling rivalry is particularly intense when children are very close in age and of the same gender and/or where one or both children are intellectually gifted.