From the ICC’s web page:

First, the crime of genocide is characterised by the specific intent to destroy in whole or in part a national, ethnic, racial or religious group by killing its members or by other means: causing serious bodily or mental harm to members of the group; deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part; imposing measures intended to prevent births within the group; or forcibly transferring children of the group to another group.

Note the repeated reference to deliberate or intentional actions. So proving intent is a big question in this case.