I've played the Rackets in Twinbrook a lot, and I can say that the age discrepancies are so much worse for that family. On a normal lifespan, Max and Marigold are a couple days into their elder stage (76 and 75, respectively, if you want to get specific). Their sons are pretty close to elderhood; Dudley has a week until his elder birthday, Dennis ten days, and Bill is sandwiched in the middle with nine days. So they're not only impossibly close in age to their parents (anywhere from nine to thirteen days younger), they're also impossibly close in age to each other, since pregnancies last for three days.
The only explanation I can think of is tattoos, since tattoos reset age and all of the Rackets are tattooed.