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
Rwandan genocide president, followed by a command to kill Tutsi. The Hutu population, which had been prepared and armed during the preceding months, and maintained the Rwandan tradition of obedience to authority, carried out the orders without question. In Kigali, the genocide was led by the Presidential Guard, the elite unit of the army. They were assisted by the Interahamwe and Impuzamugambi, who set up road blocks throughout the capital; each person passing the road block was required to show the national identity card, which included ethnicity, and any with Tutsi cards were slaughtered immediately. The militias also initiated searches of houses