Final answer:
The offspring of two heterozygous parents can have one of the following genotypes: RR, Rr, rR, or rr. The genotypic ratio is expected to be 1:2:1, leading to a phenotypic ratio of 3:1 for the dominant versus recessive traits.
Step-by-step explanation:
When both parents are heterozygous, displaying the genotype Rr, and their alleles can be dominant (R) or recessive (r), the offspring's possible genotype combinations, derived from a Punnett square, are RR, Rr, rR (which is the same as Rr), or rr.
The Rr genotype can occur in two ways, as the allele can come from either the sperm or the egg, making the outcomes genotypically identical. With fertilization being a random process, it is expected that the genotypic ratio will follow Mendel's laws, resulting in a genotype ratio of 1:2:1. This genotype ratio leads to a 3:1 phenotypic ratio for the dominant versus recessive traits when observed in large sample sizes, aligning with Mendelian inheritance patterns observed by Gregor Mendel in his classic pea plant experiments.