There are ways to reverse the ageing process, such as sacrificing villagers or even your own spouse in the Chapel of Skorm. As you spend skill points to bulk up your young Hero and watch your character model transform, you get wrinkly and old and struggle to get about.
Not that Fable's morality system is perfect. After all, we're evil because we chose to be, so that's very much on us. It's a visual representation of where you stand in the eyes of your peers, signifying how they see you in the in-game world – and despite what the Hogwarts Legacy team might have feared, I don't think that Fable developer Lionhead Studios is judging us in the slightest. Sure, there's something uniquely uncomfortable about the Aryan promises of playing a good guy, but I do enjoy the concept of moralistic consequences extending to include not only how villagers respond to you, but how you actually look. Conversely, those adamant to tread the path of evil should expect horns to grow from their foreheads, their hair to darken, and their eyes to burn red in their sockets. Those of a good alignment will find themselves sprouting angelic blonde hair as their eyes turn a baleful sky blue. In Fable, as you build up your reputation as good, evil, or neutral, your appearance changes too.