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
Hutu Power and declared that any Hutu who did business with a Tutsi was a traitor to the Hutu people. The Commandments declared that "The Hutu should stop having mercy on the Tutsi" and referred to the Tutsis as "common Tutsi enemy". The Rwandan kingdom was traditionally ruled by a Tutsi mwami, or king; Historical evidence suggests that Hutu and Twa were included in government, although the Twa significantly less so than Hutu, who were more numerous. The Tutsi/Hutu divide has been referred to as a caste system. A Hutu could gain Tutsi status through marriage or through success. Tutsis, being primarily