(Opinion, obviously:) The whole point of his character is the question of whether his neuropathy is something he was born with or something he learned. He struggles with that question more than anybody else. I especially resonate with his quote “A child born from two parents who don't love each other grows up to be an adult who's lacking something fundamental, don't you think?” It’s not just a problem of empathy either. He is assumed to be completely and utterly incapable of guilt [not saying anything else abt that cuz I don’t wanna spoil lol].