It is inevitable that when a parent has more than one child, sibling rivalry ensues because there is competition between siblings in vying for parental attention. Studies have shown that the larger the family, the more intense sibling rivalry becomes. Sometimes sibling rivalry stops in early to late adolescence but oftentimes it continues throughout adulthood. Sorry to say that as long as there are sisters/brothers, sisters/sisters, and brothers/brothers, they will be sibling rivalry. I am going to say this- in order not to have sibling rivalry, have an only child!