Rosemary was the third child of Joseph and Rose Kennedy and appeared at first as a healthy baby.
However, as she grew older, it became apparent that she was developing differently than her siblings. She had difficulty with language and was prone to outbursts and aggressive behavior, which caused concern for her parents.
Joseph Kennedy made the fateful decision to arrange for her to undergo a lobotomy, a surgical procedure that would change her life forever.
Here’s a little more: https://www.historydefined.net/rosemary-kennedy/