Origins of Hutu, Tutsi and Twa on economic criteria. Formal and discrete social divisions were consequently imposed upon ambiguous biological distinctions. To some extent, the permeability of these categories in the intervening decades helped to reify the biological distinctions, generating a taller elite and a shorter underclass, but with little relation to the gene pools that had existed a few centuries ago. The social categories are thus real, but there is little if any detectable genetic differentiation between Hutu and Tutsi. Tishkoff et al. (2009) found their mixed Hutu and Tutsi samples from Rwanda to be predominately of Bantu origin, with minor gene flow from Afro-Asiatic
Origins of Hutu, Tutsi and Twa largely of Bantu extraction (60% E1b1a, 20% B, 4% E3). Paternal genetic influences associated with the Horn of Africa and North Africa are few (under 3% E1b1b), and are ascribed to much earlier inhabitants who were assimilated. However, the Tutsi have considerably more haplogroup B paternal lineages (14.9% B) than do the Hutu (4.3% B). Trombetta et al. (2015) found 22.2% of E1b1b in a small sample of Tutsis from Burundi, but no bearers of the haplogroup among the local Hutu and Twa populations. The subclade was of the M293 variety, which suggests that the ancestors of Tutsis in this