Consider this: when you live in an isolated nation with a population roughly the size of Pittsburgh, accidentally lusting after a cousin is an all-too-real possibility. But a search engine called Íslendingabók (the Book of Icelanders) allows users to plug in their own name alongside that of a prospective mate, determining any familial overlap. The site claims to track 1,200 years of genealogical information about the island’s inhabitants. Anyone with an Icelandic ID number — that is, citizens and legal residents — is accounted for, the New York Daily News reports.