especially subclades of R1b-M269, is the most common Y-DNA haplogroup found among both the Yamnaya and modern-day Western Europeans. Additionally, a minority are found to belong to haplogroup I2. They are found to belong to a wider variety of mtDNA haplogroups, including U, T, and haplogroups associated with Caucasus Hunter-Gatherers and Early European Farmers. People of the Yamnaya culture are believed to have had mostly brown eye colour, light to intermediate skin, and brown hair colour, with some variation. A 2022 study by Lazaridis et al. found that the typical phenotype among the Yamnaya population was brown eyes, brown hair, and intermediate skin colour. None of the Yamnaya samples were predicted to have either blue eyes or blonde hair. Some individuals are believed to have carried a mutation to the KITLG gene associated with blond hair, as several individuals with Steppe ancestry are later found to carry this mutation. The Ancient North Eurasian population, who contributed significant ancestry to Western Steppe Herders, are believed to be the source of this mutation. A study in 2015 found that Yamnaya had the highest ever calculated genetic selection for height of any of the ancient populations tested. It has been hypothesized that an allele associated with lactase persistence (conferring lactose tolerance into adulthood) was brought to Europe from the steppe by Yamnaya-related migrations. The geneticist David Reich has argued that the genetic data supports the likelihood that the people of the Yamnaya culture were a "single, genetically coherent group" who were responsible for spreading many Indo-European languages. Reich's group recently suggested that the source of Anatolian and Indo-European subfamilies of the Proto-Indo-European (PIE) language was in west Asia and the Yamna were responsible for the dissemination of the latter. Reich also argues that the genetic evidence shows that Yamnaya society was an oligarchy dominated by a small number of elite males. The genetic evidence for the extent of the role of the Yamnaya culture in the spread of Indo-European languages has however been questioned by Russian archaeologist Leo Klejn and Balanovsky et al., who note a lack of male haplogroup continuity between the people of the Yamnaya culture and the contemporary populations of Europe. Klejn has also suggested that the autosomal evidence does not support a Yamnaya migration, arguing that Western Steppe Herder ancestry in both contemporary and Bronze Age samples is lowest around the Danube in Hungary, near the western limits of