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
Islam in Rwanda against the soldiers and militia of the "Interahamwe". Only once the soldiers attacked with machine gun fire were the "Interahamwe" able to enter the mosque and kill the refugees. The number of Rwandan Muslims increased after the 1994 genocide due to large numbers of conversions. Many Muslims had sheltered refugees, both Hutu and Tutsi. Some converts state that they converted to Islam because of the role that some Catholic and Protestant leaders played in the genocide. Human-rights groups have documented both incidents in which Christian clerics permitted Tutsis to seek refuge in churches, then surrendered them to Hutu death-squads, as