Forty-three years ago this month in Brookline, Massachusetts, my mother and father were looking forward with great anticipation and joy to the birth of their third child. My oldest brother, Joe, was four years old, bright, strong, aggressive, with dark eyes, a fine smile. Jack, quick, slender, independent – even at three he was interested in everything and adored by everyone. My father was 30 and my mother was 28. They loved children and would be happy to have all that God would send them.

Rosemary was born September 13 at home – a normal delivery. She was a beautiful child, resembling my mother in physical appearance. But early in life Rosemary was different. She was slower to crawl, slower to walk and speak than her two bright brothers. My mother was told she would catch up later, but she never did.

Rosemary was mentally retarded.

For a long time my family believed that all of us working together could provide my sister with a happy life in our midst. My parents, strong believers in family loyalty, rejected suggestions that Rosemary be sent away to an institution. "What can they do for her that her family can't do better?" my father would say. "We will keep her at home." And we did. For years these efforts seemed to work. My parents and the other eight children tried to include Rose in everything we did. In Hyannis Port I would take her as a crew in our boat races, and I remember that she usually could do what she was told. She was especially helpful with the jib and she loved to be in the winning boat. Winning at anything always brought a marvellous smile to her face.

She loved music, and my mother used to play the piano and sing to her. At the dining table Rose was unable to cut her meat, so it was served to her already cut.

Later on, in her teens, it was more difficult for her. In social competition she couldn't keep up. She learned to dance well enough for my brothers to take her along to parties, but it wasn't easy when Rose would say: "Why don't other boys ask me to dance?"

Yes, keeping a retarded child at home is difficult. Mother always said that the greatest problem was to get other children to play with Rose and to find time to give her all the attention she needed and deserved. Like many retarded persons, Rose loved small children and wanted to be helpful with them. Often I heard her offer her assistance to Mother with a question like, "Can I take the young children rowing, Mother?"

She loved compliments. Every time I would say "Rose, you have the best teeth and smile in the family," she would smile for hours. She liked to dress up, wear pretty clothes, have her hair fixed and her fingernails polished. When she was asked out by a friend of the family, she would be thrilled. When my father became ambassador to England, Rose came to London with us and was presented to the king and queen at Buckingham Place with mother, dad and my sister Kathleen.

Mother was worried about Rosemary in London. Would she accidentally do something dangerous when mother was occupied with some unavoidable official function? Would she get confused taking a bus and get lost among London's intricate streets? Would someone attack her? No one could watch out for Rose all the time, and she was now a grown-up girl.

In 1941, when we returned to the US, Rosemary was not making progress but seemed instead to be going backward. At 22, she was becoming increasingly irritable and difficult. Her memory and concentration and her judgment were declining. My mother took Rosemary to psychologists and dozens of doctors. All of them said her condition would not get better and that she would be far happier in an institution, where competition was far less and where our numerous activities would not endanger her health. It fills me with sadness to think this change might not have been necessary if we had known then what we know today – that 75 to 85% of the retarded are capable of becoming useful citizens with the help of special education and rehabilitation. Another 10 to 20% can learn to make small contributions, not involving book learning, such as mowing a lawn or washing dishes. Only 5% – the most severely retarded cases – must remain completely dependent all their lives.

My mother found an excellent Catholic institution that specialised in the care of retarded children and adults. Rosemary is there now. She has found peace in a new home where there is not need for "keeping up", or for brooding over why she can't join in activities as others do. This, coupled with the understanding of the sisters in charge, makes life agreeable for her.

This is an extract from Hope for Retarded Children by Eunice Kennedy Shriver, which was first published in The Saturday Evening Post, 22 September, 1962.