View source for Hardy–Weinberg

The Hardy-Weinberg principle in essence assumes random union of alleles to create genotpyes. If alleles are selected independently, one from each parent, then the allele frequencies can be multiplied to generate genotype frequencies.  For instance, if there are two alleles <math>A</math> and an <math>a</math> in a population at a frequency of <math>p</math> and <math>1-p</math> respectively then the frequency of each diploid genotype is

<math>f_{AA} = p^2</math>

<math>f_{Aa} = 2 p (1-p)</math>

<math>f_{aa} = (1-p)^2 </math>