Who is John David Stier from A Beautiful Mind: A Biography of John Forbes Nash, Jr., Winner of the Nobel Prize in Economics, 1994 and what is their importance?

John David Stier was born on June 19, 1953. His parents were Eleanor Stier and John Nash. Since Nash refused to support mother and son, the child was placed in foster care. Nash saw him until 1959 when he disappeared from the boy's life and didn't reappear until the boy was twelve. He attended Amherst College on a scholarship and became a nurse.