Rosemary Kennedy, younger sister of President John F. Kennedy and the inspiration for the Special Olympics, has died of natural causes at the age of 86, the family announced on Saturday.

The oldest daughter of Rose and Joseph Kennedy, Rosemary Kennedy was born mentally retarded and lived most of her life in Jefferson, Wisconsin, at St. Coletta’s, one of the oldest organizations in the United States providing support services for people with developmental disabilities.

Her brother, Senator Edward Kennedy of Massachusetts, and other family members were with her when she died on Friday at Fort Atkinson Memorial Hospital, the family said in a statement.

“Rosemary was a lifelong jewel to every member of our family. She was always a loving presence in our lives,” the statement said. “From her earliest years, her mental retardation was a continuing inspiration to each of us, and a powerful source of our family’s commitment to do all we can to help all persons with disabilities live full and productive lives. Millions of people of all ages have greater hope today because of Rosemary,” the statement added.

Rosemary was the inspiration for sister Eunice Kennedy Shriver, who founded the Special Olympics for mentally disabled athletes