Next to questions about adolescent issues, sibling rivalry ranks right up at the top of the list of parenting concerns. I often hear things like "Why can't my two boys play together for more than five minutes without getting into an argument?" Or "How can my daughter be so cruel to her brother." Then there are those rosy myths that parents have about having a second child. They usually go something along the lines of "I thought that when I had a second child, she would keep my older child company. I thought they would play together, be pals, protect each other, be loyal," and so forth.