Roscoe, Benjamin's son, is no different than Roger Button when it comes to dealing with Benjamin’s reverse aging. Just as Roger insisted that Benjamin dye his hair and dress like a boy, so Roscoe tries to make him wear fake whiskers and eyeglasses. Roscoe isn’t just bothered by Benjamin’s age, but by Benjamin’s age relative to him. His father ought to be older than him, and Benjamin is breaking the rules by allowing himself to be younger. He is equally concerned with what is right or proper, which means Benjamin’s age is wrong simply because it goes against the rules:
It seemed to him that his father, in refusing to look sixty, had not behaved like a "red-blooded he-man"—this was Roscoe's favourite expression—but in a curious and perverse manner. Indeed, to think about the matter for as much as a half an hour drove him to the edge of insanity. Roscoe believed that "live wires" should keep young, but carrying it out on such a scale was—was—was inefficient. And there Roscoe rested. (2.1.2)
Again we see that no one sees Benjamin for who he is, nor stops to wonder at the miraculous nature of his life. It seems like most people in this story are too concerned with reputation, rules, and what is proper and normal.