Auchincloss was born in New York City, the daughter of stockbroker
Hugh D. Jr. and socialite
Janet Auchincloss (née Lee). She was named after her mother (and was referred to as "Janet, Jr" by friends and family) while her middle name was in honor of her paternal grandmother, Emma Jennings. She had a younger brother, James Lee (known as "Jamie", born in 1947). 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). In the winter of 1945, Auchincloss was christened at the St. John Episcopal Church in
The Plains, Virginia, and was raised in the faith. She was educated at the
Potomac School in
McLean, Virginia, and
Miss Porter's School in
Farmington, Connecticut, the
alma mater of her half-sisters Jacqueline and Lee. She went on to study music history at
Sarah Lawrence College before leaving in 1966 to marry. Before meeting her future husband, Auchincloss briefly dated future Secretary of State
John Kerry. On August 17, 1963, Auchincloss was
formally presented to society at a ball held at
Hammersmith Farm, her childhood home in
Newport, Rhode Island. ==Personal life==