The genotype is required for you to use a punnet square. In the construction of a punnet's square, the genotypes of both parents are required. In the three by three square, the first column shows the genetic representation of one parent and the first row shows the genotype of the other parent. The two are combined, and they yield a genetic combination of both parents, giving all the possible outcomes of the offspring's genotypes. Using the punnet's square, you can be able to identify the percentage of the offspring that will be heterozygous or homozygous.