I've always wondered why old people are always depicted with southern accents. On a Farscape episode when John Crichton was made to age unnaturally, somehow he acquired not just gray hair and wrinkles but a southern accent. On a Stargate episode the same thing happened to Jack O'Neill. How does age make you acquire an accent from a region in which you perhaps have never even lived?
John McWhorter gives an explanation for this in a post at Language Log. Back when TV role stereotypes were developing, there had been mass migration from rural to urban locales, and older people tended to have more rural manners of speaking, including stronger southern accents in some cases. Somehow the more rural ways of speaking got associated with age. He points out that this makes no sense given today's demographics, but it makes even less sense given a science fiction character's unnatural aging. Why should your accent change if your cells prematurely start to degenerate?