My own theory on this sad saga is Joe Kennedy raped his daughter and had her lobotomized to shut her up.
And why is that my theory? Nothing more than Joe was a nasty, remorseless criminal whose evil passed quite smoothly to at least three of his sons.
Know the History of the boys, it would not surprise me to learn that the shut up was to prevent her telling how the boys raped her during her childhood. The Kennedys are a sick bunch of animals. Just right for democrip voters.