Several studies have highlighted the low genetic diversity in Västerbotten and at the same time the pronounced genetic difference between the population of Västerbotten County in northern Sweden and the population in southern Sweden. This causes rare genetic variants to be more common which has medical relevance in several ways. The effect of these rare variants can be more easily studied under these conditions and knowledge of occurring genetic variants can help in diagnosing medical conditions. This makes it important to understand the development and geography of the population from a genetic perspective. At least three possible explanations of the low genetic diversity and genetic difference, alone or in combination, can be suggested: 1. The population is a unique mix of different migration waves that might be relatively resent. 2. The population stems from a small founding population that might be relative resent and since lived in relative isolation. 3. The population stems from quite old migrations that since remained in the area. The use of gene tests to shed light on these matters is possible due to the rapid development of gene testing technology making mass testing of whole genomes possible. The way the genes mutate over time allows us to get a unique insight to the development of populations long before written sources. This can be used as an important complement to history, linguistics and archaeology in understanding how populations evolved. DNA tests give unique insight to the development of populations long before written sources. This can be used as an important complement to history, linguistics and archaeology in understanding how populations evolved. In this project we will focus on using this developing DNA technology in combination with parish registers to shed light on the question: How did the population of Västerbotten come to be? 1. Is the low genetic variability due to a small population base or cousin marriages 19:century. This can be answered combining analysis of DNA and parish registers. 2. How has demographics and migration shaped the population during the period with recorded sources, from 1700 onwards. 3. What can the Y chromosome and mitochondrial lineages as well as autosomal tests can tell us about the origin distribution of the population. Can for example the population be divided in coastal, inland and settler groups?