Barely four hundred thousand inhabitants, and yet a real demographic vertigo. In Iceland, the population is so small that kinship ties cross paths faster than one might expect. So, before pushing things too far on a date, it’s best to pull out your phone—not to exchange numbers, but to check that you don’t already share a great-grandfather.
- The Íslendingabók genealogical base, created in 1997, traces 1,200 years of Icelandic family history and covers 95% of residents over the last 300 years.
- The ÍslendingaApp app, launched in 2013 by three students, allows two smartphones to be brought together to instantly detect a too-close kinship link.
- Despite international media attention, the app had only been downloaded 3,651 times on Android, a figure in line with Iceland’s small population.
- 400,000 inhabitants, a single genealogical tree: the Icelandic peculiarity
- ÍslendingaApp, the app that turns every smartphone into a cousin detector
- “Bump the app before you bump in bed”: when technology enters dating
400,000 inhabitants, a single genealogical tree: the Icelandic peculiarity
According to the latest figures from Statistics Iceland, the island counted 394,324 residents at the start of the year, and around 396,500 by mid-2026. A population size comparable to that of a major French urban area, yet scattered across an entire country. This demographic rarity has a direct consequence: in such a small population, family trees inevitably intersect, sometimes within very close generations.
It is to document precisely these connections that the Íslendingabók database was created in 1997, the result of the collaboration between deCODE Genetics and computer scientist Friðrik Skúlason. By compiling census data, parish registers and family archives, the creators built a national genealogical tree that extends back 1,200 years. A painstaking effort that verges on an archival feat.
The result is impressive on paper: the database claims information on 95% of Icelanders who lived in the last 300 years. It remains freely accessible to anyone with an Icelandic national identification number, making it a public tool usable by all citizens and legal residents of the country.
ÍslendingaApp, the app that turns every smartphone into a cousin detector
In 2013, to celebrate the ten-year anniversary of Íslendingabók, deCODE Genetics and the University of Iceland’s school of engineering launched a student contest. The goal: imagine new, creative uses for this genealogical database, which until then had been mainly consulted out of familial curiosity. Three software engineering students, gathered under the name Sad Engineer Studios, came up with an idea that was both simple and effective.
Their app, named ÍslendingaApp, directly relies on the national genealogical register to instantly identify kinship links between two users. It targets a very concrete objective: preventing accidental consanguinity within an insular population of roughly 400,000 people, where two strangers who like each other might unknowingly share a relatively recent ancestor.
The mechanism is a single technical gesture, as playful as it is efficient. Two users bring their Android smartphones closer together; the app cross-checks their data from Íslendingabók and displays the result in a few seconds. If the kinship is deemed too close, an alarm automatically goes off, a genealogical warning signal in effect.
This student project did not remain anecdotal, as the team won the competition, taking home a prize of one million Icelandic crowns. A reward that, in passing, validated the social usefulness of an app born from a real constraint rather than a mere technical exercise.
“Bump the app before you bump in bed”: when technology makes its way into dating
The slogan chosen by the creators left no room for doubt about the intended use: “Bump the app before you bump in bed,” literally “tap the app before taking the next step.” A tagline with direct humor that neatly captures the cheeky yet practical spirit of the project, widely reported by international press as soon as it appeared in 2013.
In practice, adoption remained modest. According to figures shared with NBC News, the app had been downloaded 3,651 times at the time of its publicity, and only on Android; an iPhone version was contemplated but not guaranteed by the schedule. The figure nonetheless aligns with the size of the population involved.
Beyond the amusing anecdote, this initiative illustrates a well-documented scientific reality: Iceland has long served as a privileged testbed for population genetics. Proof that the topic remains timely, deCODE Genetics published in January 2025 in Nature a complete map of human recombination, drawing on the same family databases that feed Íslendingabók.
Thus, ÍslendingaApp is not merely a party gadget. It embodies, with a knowingly light touch, a real demographic challenge that Iceland has faced for centuries. Between playful humor and genealogical rigor, this app reminds us that in the realm of dating, a good kinship detector can be as useful as a conventional dating app.
