A few days ago we published a paper on genomic and strontium variation in Viking-age Sigtuna, but most of the response so far has been on a news-paper article referring to it. The news-paper article describes the study, but in the end of it I go beyond this particular paper when I am quoted saying “there are no proper genetic swedes”. A better and less regional (and perhaps less provocative) way of saying the same thing would have been that genetics is useless to define nations, any nations. And one reason for that is naturally that the genetic map changes all the time. Partly due to mutations, but mainly due to geneflow (migration) and drift (random processes, a plague where most of a population is wiped out for example). Since we started studying demography with chronological genomics we and others have revealed several major migratory events (the colonization of northern Europe after the glaciation, the Neolithisation, the Yamnaya-expansion, and now the Iron age mobility), and also smaller events. In the scientific press there are five chronological genomic stratas in Europe fairly well described by now (the Hunter-gatherer stone age, the Neolithics, parts of the Bronze Age, the late Iron Age, and naturally our contemporary time). And each geno-geographic map looks more or less different from the others. Due to migration and drift. We have picked up bits and pieces from many different parts of the world over our existence (although at some point all has some kind of root in Africa). That is why nationality has to be based on something else (this is not my expertise, but I suspect laws, administration, traditions, such things) than genetics.