Just a theory. What if, mom was a criminal, she carried venereal diseases and during birth gave it to her children. She had three of them. Two boys, then a girl. At some point the girl dies and she never reports it. No one even misses the girl. She takes on the girls identity. Erasing one identity while manipulating the girls identity into what she wants. Clearly this is not legal. But she somehow gets away with it. Perhaps she worked for a government department and had access to being able to make false documents? Perhaps her sons had to go along with this criminal activity of hers or suffer the consequences? I think the Zodiac Killer was a trio. A family affair. Mother and sons.