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Researchers have successfully identified annual changes in genetic ancestry within Finland

Commercially available gene tests that shed light on an individual’s ancestry are common. They provide an appreciation of the geographical regions one’s ancestors came from. To arrive at such an estimate, an individual’s genetic information is compared with information about reference groups collected from around the world.

The findings of researchers from the University of Helsinki, Aalto University and the Finnish Institute for Health and Welfare allow, for the first time, similar comparisons to be made within Finland.

A research group at the University of Helsinki, headed by Associate Professor Matti Berenen, who directed the study, has produced very detailed information on the genetic makeup in Finland. In the recently published study, reference groups of Finns with similar genetic origins were pooled and then applied to trace the effects of 20th century migration at a population level.

The results have been published in PLoS Genetics magazine. Additionally, the researchers launched a project website, where anyone can browse the results using an interactive map.

The work is based on samples collected in a FINRISK study conducted by the Finnish Institute for Health and Welfare. Using reference data sets compiled from samples, Finns can be classified at three different levels according to their geographical origin with fairly high accuracy. The first level separates the Finns on the east-west axis, while the ten different reference groups at the most detailed level correspond in part to the former provinces of Finland.

The model used for comparison works best when most of an individual’s ancestors are from the same geographic region. The more dispersed the ancestors, the less accurate the estimate provided by the model.

“Determining the genetic lineage at roughly the county level in Finland would be interesting to anyone interested in modern history,” says Senie Kirmenen, who recently published a PhD thesis on the topic at the Institute for Molecular Medicine in Finland (FIMM).

Moreover, the study observed the effect of modern genetic mixing in different regions of Finland based on people’s year and place of birth. No study of this temporal and geographic accuracy has ever been performed anywhere in the world.

According to the results, the genetic effect of the evacuation of the Karelian region ceded to the Soviet Union was greater than that of the post-war urbanization. Moreover, clear differences were observed within Finland regarding the extent of population mixing that occurred in the period covered by the study, from the 1920s to the 1980s.

The most noticeable change was observed in the regions of Uusima, Farsinais-Sumy and Hami, where the share of the southwestern breed decreased by more than 20 percentage points. Changes of this magnitude and speed illustrate migration within the country and indicate that more people migrated in the 20th century from East to West than in the opposite direction in Finland. The least change is observed in the Ostropothnia region.

“By observing the share of Karelian ancestry in the newborn population in the areas studied, we can track the movement of evacuees on an almost annual level. For example, Karelian ancestry in Ostropothnia appears to have increased greatly in wartime. However, in the 1950s it had already largely disappeared from the area, unlike Uusimaa and southwestern Finland where the share of Karelian ancestry appears to have stabilized at the wartime level, says associate professor Pirinen.

According to the research group, a detailed understanding of the exact genetic structure of a population is also important for medical projects that use genetic information.

“Finally, we want to emphasize that the genetic background is not the same as the national or cultural identity, which means that our results cannot be used to determine who is a Finn,” says Berenen.

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