Based on answer options I've seen for this question elsewhere, I'd list contributing factors increasing the likelihood of genocide as these:
- economic, political, or social instability
- unequal distributions of power and resources
- leaders who increase tensions between groups
An example would be the genocide that occurred in Rwanda. The genocide in Rwanda had arisen out of problems created by colonialism in that country. The Dutch colonial government had favored the Tutsi people over the Hutus. (The factor of leaders increasing tension between groups.) That created unequal distribution of power and resources. When the Dutch pulled out of the country, the postcolonial situation was one of great economic, political and social instability. All of this played into the violence by Hutus against Tutsis when the Hutus came into power in Rwanda.
