Genetic history of the British Isles - British Isles,Prehistoric Britain,British Iron Age,Settlement of the British Isles,Historical immigration to Great Britain,Stephen Oppenheimer,Bryan Sykes,DNA,Haplotype,Mitochondrial DNA,Haplogroup A (Y-DNA),Haplogroup R1b (Y-DNA),Haplogroup E1b1b (Y-DNA),Population bottleneck,Atlantic Europe