This work explores what scientists and researchers are discovering about sibling bonds, the longest-lasting relationships we have in our lives. From the time we, are born, our siblings are our collaborators and co-conspirators, our role models and cautionary tales. They teach us how to resolve conflicts and how not to, how to conduct friendships and when to walk away. Our siblings are the only people we know who truly qualify as partners for life. In this book, the author explores the complex world of siblings in a way that is equal parts science, psychology, sociology, and memoir. This book examines birth order, twin studies, genetic encoding of behavioral traits, emotional disorders and their effects on sibling relationships.