Cox was born and raised in the Birmingham, Alabama suburb of Mountain Brook, the daughter of businessman Richard Lewis Cox (January 28, 1931 - September 3, 2001) and his wife Courteney (nee Bass, later Copeland). She has two older sisters, Virginia and Dottie, and an older brother, Richard, Jr. Her parents divorced in 1974 and her mother was remarried to businessman Hunter Copeland (uncle to Ian Copeland). After graduating from Mountain Brook High School in Mountain Brook, Alabama, Cox left for Mount Vernon College in Washington, D.C. but did not complete her architecture course, opting instead to pursue a career in modeling and acting.