She was the half sister of the former First Lady of the United States, Jacqueline Kennedy Onassis, and socialite Princess Lee Radziwill.
In addition to elder half-sisters Jacqueline and Caroline (known as "Lee"), from her mother's first marriage to stockbroker John "Black Jack" Bouvier III, she had three elder half-siblings from her father's previous marriages: Hugh III (known as "Yusha", 1927–2015), Nina, and Thomas "Tommy" Auchincloss (born 1937).
[2][3] In the winter of 1945, Auchincloss was christened at the St. John Episcopal Church in The Plains, Virginia, and was raised in the faith.
[6] On August 17, 1963, Auchincloss was formally presented to society at a ball held at Hammersmith Farm, her childhood home in Newport, Rhode Island.
[7] On July 30, 1966, she married Lewis Polk Rutherfurd, a recent graduate of Princeton University and future financier.