WILLIAM James Sidis, who was born in 1898, was regarded by many people as the most intelligent person in the world.
His father, a psychologist, believed he could teach James to be a genius. When he was three years old James studied extremely complicated maths, the kind most people study only at university.
When he was five he wrote a long article about medicine. He was a genius, but it was not possible to tell whether this was because his father taught him or because he had a special talent.
James was ready for university when he was nine, but the school thought he should wait until he was 11. When he was 12 he gave a speech that was so complex that other students and some of the lecturers could not understand it. - bigsiteofamazingfacts.com; wikipedia.org; everything2.com