Miriam Longstreet (1895–1971). The couple raised him as their son to avoid the social stigma that accompanied birth outside of wedlock at that time. Family, friends and even young Ted were told that his grandparents were his parents and that his mother was his older sister. Bundy eventually discovered the truth about his family, although his recollections of the circumstances varied; he told a girlfriend that a cousin showed him a copy of his birth certificate after calling him a "bastard, but he told biographers Stephen Michaud and Hugh Aynesworth that he had found the certificate himself. Biographer and true crime writer Ann Rule, who knew Bundy personally, wrote that he did not find out about his true parentage until 1969, when he located his original birth record in Vermont] Bundy expressed a lifelong resentment toward his mother for never telling him about his real father, and for leaving him to discover the truth about his paternity for himself.

Bundy occasionally exhibited disturbing behavior at an early age. Louise's younger sister, Julia Cowell, recalled awakening from a nap to find herself surrounded by knives from the kitchen, and her three-year-old nephew standing by the bed, smiling. In some interviews,Bundy spoke warmly of his grandparents and told Rule that he "identified with " "respected" and "clung to" his grandfather Samuel.