Origins of Hutu, Tutsi and Twa of neighboring people, it was almost non-existent among Rwandan Tutsi. Presence of the sickle cell trait is evidence of survival in the presence of malaria over many centuries, suggesting differing origins. Regional studies of the ability to digest lactose are also supportive. The ability to digest lactose among adults is widespread only among desert-dwelling nomadic groups that have depended upon milk for millennia. Three quarters of the adult Tutsi of Rwanda and Burundi have a high ability to digest lactose, while only 5% of the adults of the neighboring Shi people of eastern Congo can. Among Hutu, one in three
Hutu Power public life, complete segregation of Hutus from Tutsis, and complete exclusion of Tutsis from public institutions and public life. Hutu Power ideology reviled Tutsis as outsiders bent on restoring a Tutsi-dominated monarchy, and idealized all things Hutu. The Commandments declared that any form of relationship between Hutus and Tutsi women was forbidden; and that any Hutu who "marries a Tutsi woman", "befriends a Tutsi woman", or "employs a Tutsi woman as a secretary or a concubine" was a traitor to the Hutu people. It denounced Tutsis as dishonest in business whose "only aim is the supremacy of his ethnic group";