The list I provided is based on general knowledge of European genetics, historical migration patterns, and geographical proximity. However, it isn't derived from a specific study or source. Instead, it reflects broader trends observed in population genetics.
For a more rigorous and precise comparison of genetic similarity between populations, scientific studies in population genetics, such as those using data from the Human Genome Project, the 1000 Genomes Project, or other large-scale genetic databases, would be needed. These studies typically use data from genetic markers like Single Nucleotide Polymorphisms (SNPs) to measure the genetic distance between populations.