Hugh Dudley Auchincloss Jr. was born on August 15, 1897 in Newport, Rhode Island, United States to Hugh Dudley Auchincloss, a merchant and financier, and Emma Brewster Jennings.
The first Auchinclosses arrived in the United States in 1803 and established a business in the import and distribution of yarn. They later branched out into dry-goods, merchandising and investments in nitrates, rail-roads, banking, and real estate.
The family name is intertwined through marital and business alliances with such famed American families as the Rockefellers, Tiffanys, and Vanderbilts. Among his relatives were his cousin, Louis S. Auchincloss, the novelist and New York lawyer, and James C. Auchincloss, the longtime representative of New Jersey's Third Congressional District in the United States House of Representatives.
Much of his considerable inherited wealth came from his mother, who was the daughter of Oliver B. Jennings, one of the founders of the Standard Oil Company.