Why did Michelangelo want to become an artist?

According to a movie I saw once, Michelangelo was illegitimate and his father noticed he had a talent for drawing. So Michelangelo was apprenticed to be a painter. When he was 14, his master let him paint one panel on an alter piece. It was so good, they say his master never painted again. Michelangelo did painting, sculpting (david) and architecture. He was the one responsible for the dome of St Peters. The largest dome in thousand years. He used a parabola. Michelangelo thought of him self as a philosopher and a friend painted him in among the philosophers in the painting the Academy.