Since Robert F. Kennedy’s assassination on June 6, 1968, his widow, Ethel, has been his torchbearer. Unlike her late sister-in-law, Jackie Kennedy Onassis, she never remarried, never sought a path or identity that was hers alone. She held herself up as the martyr, the good Catholic widow left to raise 11 children alone, the empress of Hickory Hill.She was content to be the other Kennedy widow, the domesticated antidote to the glamorous, globe-trotting Jackie.Today, Ethel Kennedy is 87, the clan’s de facto matriarch — a dubious position given the neglect shown toward her own children.Modal TriggerIn his new book, “RFK Jr.: Robert F. Kennedy Jr. and the Dark Side of the Dream,” author Jerry Oppenheimer delves into Bobby’s upbringing — or lack thereof — to understand why the scion of our greatest political family has never accomplished much. Oppenheimer contrasts Bobby’s upbringing to that of John F. Kennedy Jr.“John, after his father’s death, was brought up by a controlling and domineering mother, but one who obsessively looked out for his care and well-being,” he writes. “Bobby, after his father’s death, was essentially given up by his angry, widowed mother.”Problem childEthel Kennedy met her future husband in December 1945 on a ski trip with her college pal Jean Ann Kennedy, Bobby’s little sister. Ethel was 17 and smitten.“Her only interest was the Kennedy family,” Oppenheimer told People magazine in 1991. “The Kennedy name, what Bobby could do in the future, what the other Kennedys were doing, what Jack’s future was. She just gave her life over to them.”They married in June 1950, and by July 1951, their first child, Kathleen, was born. Ethel spent much of the decade pregnant, but that didn’t stop her from traveling extensively with Bobby in pursuit of his political future.The children, Oppenheimer writes, were afterthoughts. Bobby, the third-eldest, was a sensitive boy who turned to animals for company. There was little adult supervision.“It was incredible,” a former nanny told Oppenheimer. “There wasn’t anybody to say, ‘Don’t do that.’ It was hard to control them.”Ethel was 40 and three months pregnant with her last child, daughter Rory, when her husband was assassinated. Bobby Jr. was 14, and one week after his father’s funeral, the family celebrated his brother’s 13th birthday. Bobby slipped laxatives into everyone’s drinks as a prank.“Just leave home!” Ethel yelled at him. “Get out of my life!”She often used such language with him. “Her moods could swing drastically,” Oppenheimer writes, and soon after, she “literally beat Bobby with a hairbrush.”Modal TriggerRobert Kennedy Jr. and mom Ethel at his father’s funeral in 1968.Photo: WireImageUnable to cope with her grief — let alone her children’s — Ethel shipped Bobby off to a series of boarding schools, each less prestigious than the last, each forced to expel the namesake son of a martyred political icon.Bobby wasn’t even 15 and was already using drugs heavily. He insisted each school allow his pet falcon to stay in his room. He formed a gang, The Hyannis Port Terrors, and one of his favorite practical jokes was bumping the fender of a passing car, having a pal collapse in the road, then yelling, “You’ve killed a Kennedy!” He once spat in a cop’s face.Ethel did nothing. She was sealed off in her McLean, Va., estate. Only her dead husband, his legacy and her privilege as a Kennedy widow existed. Nothing Bobby did got her attention for long, and that attention was usually negative.“I never witnessed a civil conversation between Bobby and Ethel,” one of RFK Jr.’s ex-girlfriends told People in 1984.When Bobby was arrested for buying pot in 1970, Ethel threw him in the bushes. “You’ve dragged your family’s name through the mud!” she yelled.“Almost anything could trigger a fight between them,” another family friend said. “She would scream at him for 10 or 15 minutes without letting up and tell him to leave, which he did. Later, it would be like it never happened.”‘Horror Hill’In his 1994 biography of Ethel, “The Other Mrs. Kennedy,” Oppenheimer writes of her “uncontrolled rage” and the abuse that extended to her household staff. Her brother-in-law Peter Lawford was shocked when Ethel berated a new maid for going to throw out some old scraps of paper.“You stupid n- - - -r,” Ethel yelled. “Don’t you know what you’re doing? You’re destroying history. Get out of my sight! You’re fired.”One of Ethel’s secretaries, Noelle Fell, told Oppenheimer she was surprised by such outbursts.“She would say things like, ‘Those black people are stupid,’ ” Fell recalled. “I really don’t think she liked blacks or Hispanics. She couldn’t stand it if they didn’t speak English.”One such maid, who brought sanitary pads when Ethel asked for face cream, got a hard slap in the face. She quit on the spot.Modal TriggerRobert and Ethel Kennedy pose with their children (from left) Joe, David (standing), Bobby Jr. (sitting), Kathleen and Courtney.Photo: Getty ImagesSuch high turnover contrib