For the genotypic frequency to remain the same over generations, then according to Hardy-Weinburg, the following five assumptions are presumed;
1. That the population is large enough for sampling hence there is no genetic drift
2. Natural selection is not acting on the population
3. No gene flow between the population being studied with another population occurred either through migration etcetera
4. No/negligible mutations occurred
5. Mating between individuals of the population is occurring randomly