Origins of Hutu, Tutsi and Twa on economic criteria. Formal and discrete social divisions were consequently imposed upon ambiguous biological distinctions. To some extent, the permeability of these categories in the intervening decades helped to reify the biological distinctions, generating a taller elite and a shorter underclass, but with little relation to the gene pools that had existed a few centuries ago. The social categories are thus real, but there is little if any detectable genetic differentiation between Hutu and Tutsi. Tishkoff et al. (2009) found their mixed Hutu and Tutsi samples from Rwanda to be predominately of Bantu origin, with minor gene flow from Afro-Asiatic
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