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

Martha Nash was the sister of John. She graduated from the University of North Carolina at Chapel Hill and traveled to Santa Monica with John for his second summer at RAND. She married Charlie in spring of 1954 and had two children. She had her brother committed several times and remained estranged from him until the 1980s.