The fusion of the sperm (male gamete) and the egg (female gamete) results in the formation of the zygote which develops into an embryo differentiating into a fetus (offspring). Punnett square is used to predict the genotypes of a cross or breeding experiment. It is the graphical representation of the possible outcome of the offspring or the zygotes resulting from the fusion of the male and female gametes. Baby of Joe is one of the representation shown as one of the four possible outcomes in the Punnett square.