BOSTON - When a young John Kerry launched his first election campaign in 1972, he tapped his 21-year-old brother, Cameron, to serve as his political director. More than three decades later, the soon-to-be Democratic presidential nominee — now surrounded by a cadre of high-paid, high-powered political professionals — still relies heavily upon his little brother as a top adviser, fund-raiser, sounding board and confidant. Over the past two years, the Massachusetts senator has consulted with Cameron before making the most monumental decisions of his presidential quest: how to vote on the Iraq war resolution, whether to fire the manager of...