intellectual disabilities in children, especially in an era in which eugenics advocates routinely declared intellectually disabled children to be "genetically unfit", only the closest family friends were allowed to know about Rosemary's condition. To most other visitors to the Kennedy family home, Rosemary's failure to interact the way her siblings did was put down to her "shyness."

Rosemary tried her best and apparently functioned as borderline normal for most of her childhood. It was only when she reached her early twenties that her condition grew worse. Whether due to grief at being unable to live up to her parents expectations or for other reasons, she began acting out and became more difficult for her family to control. Along with gaining a great deal of weight, she had also becomesexually mature and the "shy child" excuse no longer worked. Not only was Rosemary unable to "pass" as a normal child, but she was also prone to violent tantrums, including throwing objects and physically assaulting family members. In the summer of 1941, she even assaulted her grandfather, John J. (Honey Fitz) Fitzgerald

John and Rose Kennedy began searching for a solution to deal with their disturbed daughter. Not only were they worried about her violent acting out, but her sexual maturity meant the increasing possibility of a scandal that might damage the future political careers of the other Kennedy children. Even then, John Kennedy Sr. had every intention of seeing one of his sons as President of the United States in time and the stigma that Rosemary brought to