def hardy_weinberg_principle(minor_allele_frequency):
  """
  given a minor allele frequency for a biallelic variant, 
  return an array of frequencies for each genotype
  """
  p = 1-minor_allele_frequency
  q = minor_allele_frequency
  aa = p * p
  aA = 2 * p * q
  AA = q * q
  return [aa, aA, AA]