Superheroes, for the most part, don’t age. Marvel and DC have their superhero universes set in some sort of sliding scale timeline, where almost everything that’s happened since the superhero line was created somehow only occurred over a ten to twelve year period. That means that even though there are Fantastic Four comics depicting Reed Richards and Ben Grimm in the trenches of World War II, today neither of those gentlemen are that old. Aside from a handful of World War II era heroes and villains who have managed to stay active and keep their ties to the war (Captain America, the original Justice Society), or even the rarer other type (Frank Castle is a Vietnam vet), heroes are pulled from eras they existed in to avoid explaining how Batman swings through the streets of Gotham without a walker.
But there are ways to allow heroes to age, and one of them DC used to have was Earth-2. Originally the home of the Justice Society of America, Earth-2 was the place where the Golden Age heroes did their thing. And while none of them quite reached the state we’d consider “elderly,” some of them did marry and have children. One of them was the Earth-2 Batman, and he had a daughter, and oh man, is this one messed up history.