Demi Moore was born Demetria Guynes on November 11, 1962, in Roswell, New Mexico, the United States. Her parents split up two months before she was born, and she was raised by her mother and stepfather, Virginia and Danny Guynes, both of whom drank heavily.
Moore learned of her biological father, Harmon, at age 13, when she found her mother and stepfather's marriage certificate and inquired about the circumstances since she "saw my parents were married in February 1963. I was born in '62." Her biological father was an Air Force airman Charles Harmon, Sr., who was not present in Moore's life. Moore said in 1991, "My dad was Dan Guynes. He raised me. There is a man who would be considered my biological father who I don't really have a relationship with."
Along with her mother, half-brother, and stepfather, Moore had moved more than 30 times by the time she turned 14, eventually settling in Los Angeles. The problems that went along with such an itinerant lifestyle were compounded by the dysfunctional, sometimes abusive relationship between Moore's mother and stepfather. The latter committed suicide when Moore was fifteen, around the time that she discovered that he was not her biological father. Moore later explained in Interview magazine that "By moving around a lot, I learned to assimilate into whatever new surroundings I had and to become very comfortable with people quickly. I think that was one of the strongest contributing factors to my becoming an actor."
When Moore was 16, she left home and distanced herself from her family. Demi's mother had a long arrest record which included drunk driving and arson. Moore broke off contact with her completely when Guynes walked away from a rehab stay Moore had paid for at the Hazelden Foundation in Minnesota. Moore's mother was diagnosed with brain cancer in 1997, and the mother and daughter finally reunited. Moore stayed with her mother for the final months of her life. Virginia Guynes succumbed to her disease in July 1998.
Demi Moore kept her first husband’s last name professionally. Legally, though, she doesn’t use any of her three husbands’ names. She goes by her maiden name: Demi Guynes.