Phenotypic variation within the British population
Using my TraitMap tool, which only analyzes a small number of SNPs associated with traits like pigmentation and other appearance-related genes, we can see how populations cluster based specifically on those trait markers.
For this example, I looked only at GBR (British from England and Scotland) samples from the 1000 Genomes dataset. When we run PCA using just the GBR population, we see variation even within that single population.
The predicted appearances of the two highlighted individuals illustrate this clearly. HG00261 is the dark-haired (dark brown), dark-eyed individual plotted on the far left. HG00141 is the light-haired (light blond), light-eyed individual plotted on the far right. These predictions come directly from their genotypes at trait-associated SNPs.
It is also notable that HG00261 is predicted to have more Northern European ancestry than HG00141 according to the Globe13 calculator. This demonstrates that admixture percentages do not directly correlate with appearance. Visible traits are influenced by a very small number of SNPs compared to the full genome. Also keep in mind that services like 23andMe only analyze about 0.1% of the genome using selected SNP markers rather than sequencing the entire genome. So the differences we observe between human populations come from variation at a small subset of SNPs within that already tiny fraction of the genome.
Overall, humans are genetically extremely similar, and differences in appearance are largely driven by variation at a small number of trait-associated SNPs rather than differences across the genome as a whole.
Posted Feb 26, 2026, 7:56 AM UTC