When anti-virus software entrepreneur Friðrik Skúlason teamed up with a genetics company to create genealogy website Íslendingabók (the Book of Icelanders), the idea was to map the family connections between the citizens of Iceland. However, since its launch in 2010, the project has morphed into something much more, spawning a new mobile app that is now being used to check if Icelandic natives are dating close family relatives.

The app has an "incest alarm," discreetly warning users of a potentially awkward situation

The app was launched as part of a competition by the website owners to help make the Book of Icelanders available on an Android smartphone, offering 1 million Krona (around $9,160) to the makers of the best app. The winning app— ÍslendingaApp SES from Icelandic app developers Sad Engineer Studios — not only helps users learn about their family from wherever they are, it also features a "bump" feature which essentially allows two Android smartphones to be bumped together to check if there's a potentially embarrassing family reunion about to happen. If there is, an "incest alarm" discreetly warns both users.

Although Iceland now has over 300,000 inhabitants, every one of them has descended from the same family tree. In this sense, it's not a question of if you are related to someone, it's a matter of how closely. Skúlason has previously played down the use of the service as a tool to avoid incest, but with the new smartphone app including features like an incest alarm, the website founder may have accepted that the Book of Icelanders has taken on a life of its own.