A woman has two dominant traits, each caused by a mutation in a different gene: cataract (an eye abnormality) which she inherited from her father, and polydactyly (an extra finger), which she inherited from her mother. Her husband has neither trait. If the genes for these two traits are 15 map units apart on the same chromosome, what is the chance that the first child of this couple will have both cataract and polydactyly?