Playwright Arthur Miller has a secret son with Down's syndrome, who he hid from the world. Daniel Miller, whose mother was the writer's third wife Inge Morath, was put into an institution when he was just one week old and cut out of his father's life. Miller failed to mention Daniel, now 40, in his memoir and only acknowledged him on his deathbed in 2005, at the age of 89, when he wrote a will giving his son an equal share in his estate with his other children Jane, Robert and Rebecca - who is married to Daniel Day-Lewis. The revelations come in an explosive article in Vanity Fair magazine, which includes quotes from friends of the Death Of A Salesman writer - who was once married to Marilyn Monroe. It claims Day-Lewis - who won an Oscar for his portrayal of a disabled man in My Left Foot - was appalled when he learned of the secret, and pushed Miller to reach out to his lost son. After leaving the institution at 17, Daniel moved into an apartment with friends and held down a number of jobs. He was an accomplished athlete and competed in the Special Olympics. The pair were reunited in 1995 when Daniel attended a speech his father gave, and embraced him. Disabled rights activist Jean Bowen reveals, "Danny was thrilled. He (Arthur Miller) was absolutely amazed at Danny being able to live out on his own." Rebecca Miller tells Vanity Fair, "The only person who can truly answer your questions is my father and he is dead. Danny is very much part of our family. He leads a very active, happy, life, surrounded by people who love him."