Steve and Sonya's son genotype is pp. Because an inheritance of autosomal recessive disorder is with recessive allele responsible for the exceptional phenotype. In this case, Steve and Sonya are both heterozygotes, Pp, which means they both have a p allele because each one gave the boy a p, contributing to affect his son. And since we are talking about inheritance of an autosomal disorder, we know that the parents phenotypic proportions are the same.
