Friday, September 13, 2024

Fst test is a special case

 The genetic history of Finns is surprisingly poorly known. Words are used in a general sense and generalizing. It has become a habit to enhance one's own knowledge with expert vocabulary in different contexts without real context. For example, the genetic disease inheritance of Finns is used to describe the homogeneity of Finns and the old bottleneck of the Finnish population. However, this inheritance is regional, peripheral, and not even old. Regional genetic drifts are generalized to cover the homogeneity of the entire population. This is not the case, but different regions of Finland have also their own admixture, a very young Sámi mixture in the north, Swedish mixture in the west and south. Older admixtures include the Iron Age Estonian and Sami admixture of the entire population and the even older Germanic admixture.

Incorrect assumptions lead to incorrect conclusions and results. The fst results of the Estonian study, link, are right, yet could be more informative. It comes out by dividing the Finnish samples into decile groups based distances to the Estonian data. There are 10 samples in each decile and the result reflects the diversity of Finns in fst tests. The final result depends on the testing method, for example admixture tests would give a different result, but the error sources should be taken into account according to the method. I also tested with the same deciles against the British, although the decile division made on the basis of Estonian data does not give a correct picture of the Britts in relation to the Finns. 

Due to the nature of the fst test, the result based on the entire population does not give sensible fst distances of the Finns. In principle, we can take any set of samples and assume the meaning we want, but it would be better to analyze first, because every method tends to have own pitfalls.

The material has been downloaded from the 1000 genomes Project and Reichlab's Human Origin data.









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