Although Jackie Kennedy Onassis's relationships with the men in her life—her father and husbands in particular—have been the subject of much biographical attention, Pottker asserts that these were actually of less significance in shaping Jackie's identity and legacy than was her relationship with her mother, Janet Lee Auchincloss. This, then, is meant to be a dual biography, in which Pottker (Dear Ann, Dear Abby: The Unauthorized Biography of Ann Landers and Abigail Van Buren) assesses the daughter's life in relation to her mother's and traces the ways in which Janet's ideals and ambitions influenced both Jackie's life and the Kennedy White House. Claiming to have uncovered several new facts about Jackie and many about Janet, this is meticulously researched and ably narrated. But while Pottker is insistent that Janet's role in Jackie's life merits a book-length study (and certainly, her point that Janet was actively involved in her daughter's life for 60 years is well taken), this remains less a real assessment of that mother-daughter relationship than yet another retelling of the Jackie Kennedy Onassis story, with details of Janet's life thrown in. But Janet is clearly a fascinating subject in her own right and, portrayed here sympathetically but warts-and-all, seems more human and more compelling than her celebrated daughter. A ruthless social snob, for example, she was also capable of selfless and spontaneous acts of kindness; and while her obsession with money and prestige lurked behind much of the advice and social training she gave Jackie, she also appears to have been a very devoted mother. If this is a less than groundbreaking retelling of Jackie's story, it's still noteworthy for its rich and nuanced portrait of Janet. Photos not seen by PW. Agent, Pam Bernstein. (Oct.)