“She’s my sister. She’s my daughter. My sister. My daughter. She’s my sister AND my daughter.” Those classic lines from Chinatown, uttered by Faye Dunaway’s character Evelyn Mulwray, have been oft parodied since the film’s 1974 release, but who'd think that one day there would actually be an app to prevent such awkward familial relationships from occurring? There is in Iceland, where “bump the app before you bump in bed” may become the catch phrase for a generation who really do have to concern themselves with accidental incest. In a country with a population that tops out at 320,000 people, most of them distantly related, a smartphone app that warns you when you may be getting too close for comfort isn't a bad idea. According to the Landnámabók, a medieval Icelandic book, the settlement of Iceland began in 874 A.D. with the arrival of the Norse chieftain Ingólfur Arnarson. He was followed by his fellow Vikings and, on occasion, their Gaelic slaves. It was a never an immigration hotspot, and over the centuries the gene pool, albeit stellar, became somewhat limited.

The app, Islendiga-App, was created by three University of Iceland software engineering students for a contest seeking “new creative uses" of the Islendingabok, or Book of Icelanders, an online database of residents and their family trees that stretches back 1,200 years. All users have to do is bump phones to find out whether they share a grandparent (or two). While most people are likely to know whether they're first cousins, there are always surprises. Many Icelanders have had the uncomfortable experience of attending a family event and running into someone they'd hooked up with at some point in once-blissful ignorance. So far, the Islendiga-App has been downloaded nearly 4,000 times. (It's only available on Android.) Considering Iceland's homogeneous population, distant location and unusual history, it’s unlikely the app would be useful beyond its shores. However, if those “I accidentally married my (name unknown immediate relative here)” letters to advice columnists are any indication, as well as the wide coverage the app's received, the developers may be on to something.