From dark skin to fiery red hair, the world’s ethnic groups all have characteristic physical features. But how does our genome code for these differences? New research shows that it isn’t just because different groups carry different genes — some of the variation is down to the same genes being expressed differently.
The study is the latest contribution to the popular new field that uses modern genomic tools to unravel the genetic basis of variation between ethnic groups. Such analyses have only become possible recently, thanks to tools such as the International HapMap Project, published last year, which charts the prevalence of single DNA-letter differences (called single-nucleotide polymorphisms, or SNPs) between different ethnic groups.
Such work has spotted many genetic differences between groups — some of the genes that determine skin or eye colour, for example, have been unpicked. But scientists usually study one trait at a time, and only find a genetic explanation after years of painstaking work.