Charles McWilliam was born on December 26, 1950, in Pasadena, California. Charles married Katie on January 15, 1993, and they had four children: Charles Jr., Rebecca, Amy, and Jamie.
McWilliam was a professional engineer and employed by Application Engineering Company (AEC), Energy Research and Development Administration (ERDA), and the Department of Energy (DOE) in affiliation with the Nevada Test Site.