Iceland has almost everyone’s family tree in a database accessible for all the country’s approximately 335,000 citizens. Everyone is related and “there is even an Android app to show each Icelandic citizen his or her genealogy, in most cases back to 874 AD.”[1] Many people in Iceland are hobby genealogists. When my guide on a tour of Iceland in 2017 discovered my interest in genealogy, she proudly told me that her grandfather had traced their family’s ancestry to a King of Norway. That would not be unusual because Iceland was settled mostly by Norwegians who may have been seeking new land to farm.  A favorite question when meeting someone new is “Who are your people”? Since almost everyone is related it is common before dating someone new to check to see that you two are not too closely related. The fact that almost everyone is descended from just a few couples has also made Iceland a heaven for those studying genetic diseases. Additionally, the homogeneity of the population has...