the Prequels should have added a new twist by making Obiwan the father
imagine if there was a secret fling between Obiwan and Padme.
when Obiwan retells the story he says "a pupil of mine called Darth Vader betrayed and murdered your father"
his pupil did betray him (obiwan), and "murdered" him metaphorically by forcing him to go into hiding, effectively ending his life in many ways.
so he wouldn't be lying from a certain point of view.
the prequels should have alluded to such a possibility to make it all more interesting.
hint at a secret fling between Obiwan and Padme behind Anakin's back.