Is there such a thing as sibling rivalry?

Siblings. Some issues involve dominance, control, seeking attention from caretakers, or pursuit to excel.
Sibling rivalry. A well studied fact of life. 3 to 9 year olds, for example, have conflicts about once every 18 minutes, but in healthy relationships, there's a lot of positive exchanges too. The ability to resolve conflict with a sibling can be an extremely important part of growing up. When sibs do not learn how to negotiate these conflicts, they are at risk for becoming estranged. Reconciliation is possible.