Forgive me for being obtuse, but I've never really understood how Ted Bundy could believe, until 1969, that his mother was his sister. They'd left his grandparents when he was three years old, and Ted was then adopted by Louise's husband when Ted was five (1951). He took what would be (according the the story that his mother was his sister) his brother-in-law's last name. For him not to realize that his supposed sister was his mother until he was 23 years old seems far-fetched. I'm guessing that Ted told his biographers that he'd discovered the birth certificate himself as some form of ego preservation. He must have known much earlier than 1969, and experienced some bullying because of the status.