Origins of Hutu, Tutsi and Twa phenotype, genotype, cultural memory of inhabitants of Rwanda, archeology, and linguistics. Most Tutsis and Hutus carry the E1b1a paternal haplogroup, which is common among Bantu populations. More recent studies have de-emphasized physical appearance, such as height and nose width, in favor of examining blood factors, the presence of the sickle cell trait, lactose intolerance in adults, and other genotype expressions. Excoffier et al. (1987) found that the Tutsi and Hima, despite being surrounded by Bantu populations, are "closer genetically to Cushites and Ethiosemites". Another study concluded that, while the sickle cell trait among the Rwandan Hutu was comparable to that
Origins of Hutu, Tutsi and Twa area may have assimilated some South Cushitic pastoralists. In general, the Tutsi appear to share a close genetic kinship with neighboring Bantu populations, particularly the Hutu. However, it is unclear whether this similarity is primarily due to extensive genetic exchanges between these communities through intermarriage or whether it ultimately stems from common origins: [...]generations of gene flow obliterated whatever clear-cut physical distinctions may have once existed between these two Bantu peoples – renowned to be height, body build, and facial features. With a spectrum of physical variation in the peoples, Belgian authorities legally mandated ethnic affiliation in the 1920s, based