Can we know what the genotype is if we know what the phenotype is? And the answer is not always knowing. The phenotype does not always tell us what the genotype of that organism is. To determine what the genotype is, we actually have to conduct experiments, and usually the tools that we use to help us determine what the potential possibilities are for the genotype of any offspring. When we conduct a mating process, this tool is known as a Punnett square. Now, what exactly does a Punnett square tell us?