In a population of diploid organismsIf frequency of allele A=p and frequency of allele a=qExpected genotype frequency under random mating areAA=p2 (for the AA homozygotes)aa =q2 (for the aa homozygotes)Aa=2pq (for the Aa heterozygotes)(In absence of selection, mutation, genetic drift or other forces allelic frequency p and q are constant through generation)Therefore p2+2pq+q2=1