In Princely Brothers and Sisters, Jonathan R. Lyon takes a fresh look at sibling networks and the role they played in shaping the practice of politics in the Middle Ages. Focusing on nine of the most prominent aristocratic families in the German kingdom during the Staufen period (1138 1250), Lyon finds that noblemen and to a lesser extent, noblewomen relied on the cooperation and support of their siblings as they sought to maintain or expand their power and influence within a competitive political environment. Consequently, sibling relationships proved crucial at key moments in...