His oldest son is Robert Sinclair MacKay a professor of physics at the University of Cambridge .
Robert Sinclair MacKay is a professor of mathematics at the University of Warwick ; his youngest son was David J.C. MacKay .
His oldest son is Robert Sinclair MacKay , a professor of mathematics at the University of Warwick ; his youngest son was David J.C. MacKay , a professor of physics at the University of Cambridge .