What is the process of determining genotypes?

A Punnett square is one of the simplest ways to determine genotype. The square is actually a mini-chart used to determine the potential genotype for an offspring with respect to particular trait. To create a Punnett square, write all the possible alleles across the top of the square for one parent and all the possible alleles for the other parent down the left-hand side. Each listed allele will become either a column, for top alleles, or a row, for left-side alleles, inside the square. The square is filled in as you write down alleles from the top in their respective columns and then write down alleles from the side in their respective rows, creating a square full of potential genotypes.