Gene A (A and a aleles) affects hair color: A confers a dark brown coat while aa individuals have tan coats. Gene B is associated with having hair, bb individuals have no hair. A dihybrid cross is carried out, 900 offspring have dark brown hair, 400 have no hair, and 300 have tan hair. Which of the following is likely? Gene A is recessive to gene B. The expression of gene A depends on the gene B genotype; this is incomplete dominance. Gene A has one dominant allele and Gene B has one dominant allele. A and a are codominant, while B is dominant over b,.