I saw this post on Brazil. https://www.reddit.com/r/dataisbeautiful/comments/1vlyj3f/oc_brazils_violent_past_is_preserved_in_its/ Remembered hearing a similar story about Iceland. I dug up the papers https://pubmed.ncbi.nlm.nih.gov/11179019/ https://pmc.ncbi.nlm.nih.gov/articles/PMC1274484/?utm_source=chatgpt.com Mitochondrial DNA does not seem to let you drill down as much so it is more vague 'British isles'.