I wasn’t his son. That was another Charlie. Intelligence and knowledge had changed me, and he would resent me—as the others from the bakery resented me—because my growth diminished him. I didn’t want that.
This passage comes from Progress Report
Though Charlie longs to connect to and understand his past, he realizes that he has traveled too far to be able to present himself as the same person he used to be. He believes that rather than being happy for his son’s massive gains in intelligence, Matt would feel betrayed if he were to discover that the articulate and bright man before him is Charlie. Charlie thinks that Matt would feel “diminished” by Charlie’s intelligence, not just because Charlie is now far smarter than Matt is, but also because Matt invested so much energy into relating to his son as an intellectually disabled boy. For years, Matt dealt with the difficulty of having an intellectually disabled son, and he also faced the greater difficulty of trying to persuade his irrational wife to accept Charlie’s disability. Charlie fears that if a new, brilliant Charlie were to come along all these years later, Matt would feel that he had wasted all of his emotional energy and might even feel cheated. Charlie is effectively two people now, but neither person can have a whole life or a whole history.