What is the probability for each genotype?

To determine the probability of each genotype, you typically use a Punnett square or calculate it based on the allele frequencies in a population. If considering a simple Mendelian trait with two alleles (A and a), the probabilities can be calculated as follows: for homozygous dominant (AA), it’s the square of the frequency of A; for homozygous recessive (aa), it’s the square of the frequency of a; and for heterozygous (Aa), it’s twice the product of the frequencies of A and a. The total probabilities must sum to 1.