Why exactly cant jason bourne remember his past?
He gets retrograde amnesia from the trauma that he suffers when he is shot by Wombosi after a failed assassination attempt. Normally retrograde amnesia is caused by a head injury/head trauma. The reason that Bourne gets amnesia from two gunshots in the back in the movie is because Hollywood is stupid. When the book was remade into a movie script, the fact that Bourne was also shot in the head was left out which was a pretty important detail that got left out. In the book, the bullet that struck his head was what caused his memory to be blocked and would have made a lot more sense if it had been tranferred over to the movie as well.
