Iceland has an online database to prevent incest!

With a population of around 320,000, Icelanders feel it's too easy to fall in love with a distant cousin. As a response, they've created an online database that store family information for everyone with an Iceland-issued ID.

Called Íslendingabók (book of Icelanders), he website is the product of a collaboration between a genetics research company and a software entrepreneur. The site also tells you if you're related to any famous Icelanders. 

(Source)