Slate has an article (inspired by Dick Cheney’s recent linking of West Virginia to inbreeding) on the origins of the myth that inbreeding is a common or even accepted practice in WV.
They quote a historian who researched the topic specifically:
“In 1980, anthropologist Robert Tincher published a study titled “Night Comes to the Chromosomes: Inbreeding and Population Genetics in Southern Appalachia,” based on 140 years’ worth of marriage records. He concluded that “inbreeding levels in Appalachia … [are neither] unique [n]or particularly common to the region, when compared with those reported for populations elsewhere or at earlier periods in American history.”
So why the myth then? Slate attributes it mostly to the visibility of poverty in West Virginia, and a public desire to blame their poverty on some action, in this case, inbreeding.
Stereotypes about West Virginian breeding practices have long been linked to the state’s poverty. When Eleanor Roosevelt visited West Virginia mining towns in the 1930s, national newspapers ran pictures of rundown shacks and barefoot kids in rags, which left a lasting impression of the state as a backwater. West Virginians became the prototypical “hillbillies,” and incest served as a crude “scientific” explanation for their downtrodden social condition.
In more recent memory, the 2003 film Wrong Turn helped perpetuate the inbreeding stereotype. Set in West Virginia, it features cannibalistic mountain men, horribly disfigured from generations of incest. Then, in 2004, Abercrombie & Fitch released a T-shirt emblazoned with a map of the Appalachian state and the words “It’s all relative in West Virginia.” In February, a casting director for the upcoming thriller Shelter put out a call for extras with “unusual body shapes, [and] even physical abnormalities” to depict West Virginia mountain people.
Charming. The inbreeding hillbilly stereotype serves a purpose outside simply explaining poverty, as it simultaneously reduces sympathy people might otherwise feel for those in poverty. When we all accept some cultural myth that poverty is the result of something other than structural economic and political problems, in this case, a perverse activity the poor participate in, what point is there to reforms or even to charity?
Thrillers and horror movies love to exploit images of people with disabilities or working-class people to freak out the more “normal” protagonists who happen to stumble upon the lair of horror. These film narratives match the cultural narrative that led up to the offensive jokes of A&F and Dick Cheney: Low class status and abnormal physical appearance and ability are a reflection of low moral character.