The risk of Icelanders accidentally sleeping with a relative is apparently high enough to justify the creation of a smartphone app to help prevent it.

Iceland isn't a big country. Most Icelanders are descended from the Norse and Celtic settlers that first began arriving on the island some time in the 700s and 800s, with few additions to the gene pool. Roughly two-thirds of its 320,000 population live in and around the capital, Reykjavík, so the chances that you're at least not-too-distantly-related to most of the strangers you walk past in the street are high. Or, indeed, someone you might meet in a bar and go home with.

Part of the problem, beyond the small population, is that Icelandic naming conventions don't reflect someone's descendants. Neither patronymic or matronymic, instead each person's father's first name becomes the child's last name. Each new generation has a completely different name to the name of the generation that preceded it. Cousins, aunts, uncles, nieces, nephews -- all could have very different names.

The solution to this? Developers from Sad Engineers Studios created ÍslendingaApp SES(Beta), an Android app that seeks to save any incredibly awkward revelations in the future by making things clear now. It uses as its resource Íslendingabók, an online genealogical database that contains records of more than 720,000 Icelanders going back 1,200 years using as many records (church documents, census information, and so on) as possible.

The simple idea is to make those records easily available for people so they can figure out who they're related to. But the best feature is reserved for when two people who both have the app meet -- they both get their smartphones out and "bömp"(bump) them together. If they share a grandparent, the app will bring up an alert that it is most definitely not cool to go any further than a handshake with that person. The feature is called "Sifjaspellsspillir", or "Incest Spoiler".

The app won a competition held to find the best use of the is site, according to the News of Iceland, which describes the "Incest Spoiler" as "a precious feature" that will prevent the situation where "someone goes all in with someone and then later runs into that person at a family gathering some other time". This is a situation, it claims, that "everyone has heard of (or experienced)". Well, sure, if you say so.

The app has had almost 5,000 downloads since its launch a few days ago, and its 4.6/5 rating attests to it satisfying a craving clearly felt among Icelanders. However, at least one user has left a review that rues its timing: "If I'd had this in earlier maybe I would not go home with my aunt". 

Of course, all of humanity descends from a common ancestor, so technically we're all guilty of getting down with a relative of sorts. Many famous and respected people throughout history have ended up married to their first cousins, like HG Wells or Albert Einstein -- though the fate (and family tree) of Charles II of Spain should prove a warning to all of us of the health consequences of in-breeding.