Anakin Skywalker NEVER learned how to retain his identity in the Force
Do you know what happend in those 20 odd years between episodes 3 & 4 then?
Serious question is there a book the tells the story of vader from his birth up untill we meet him at the start of ANH cause' if there is id sure like to get my hands on a copy of that, but if there isnt then how can you say he never learnt how to retain his identity in the force, for all we know his master could have taught him that?