He was the great-grandson of William Stevenson , brother of US Vice President Adlai E. Stevenson , making him a second cousin once removed of two-time presidential candidate Adlai E. Stevenson II .
His grandfather Adlai E. Stevenson was Vice-president of the United States to Grover Cleveland , and his second cousin , once removed Adlai Stevenson II was Governor of Illinois and unsuccessfully ran for President twice in the 1950s losing to Dwight D. Eisenhower both times .