Warren Buffett's right-hand man has lost $100 million in past year; Berkshire Hathaway stock has dipped 22% since December highs. Omaha-bred lawyer's son spent childhood raising hamsters, perusing medical journals, captaining school rifle team. Worked for Buffett & Son, high-end grocery store run by Warren's grandfather. Math & physics major at U. of Michigan dropped out to join Air Force. Law degree from Harvard. Kicked off investing career after meeting Warren Buffett at a 1959 party. Became vice chairman of Berkshire. Donated over $20 million in Berkshire shares to California schools last fall.