Five factors are known to affect Hardy-Weinberg equilibrium. These include all of the following, except 

Random mating is a prerequisite for Hardy-Weinberg equilibrium (assortative mating disturbs the equilibrium). The Hardy-Weinberg Law states that in a large, random-mating population that is not affected by the evolutionary processes of mutation, migration, or selection, both the allele frequencies and the genotype frequencies are constant from generation to generation.