1. A 3 year-old boy is brought to a physician because the mother notices tha t the child is engaging in less active play and tires easily. During physical examination, the pediatrician notices that the child's thighs are larger than normal for age and that the child cannot stand up without using his arms to help. Further studies demonstrate a defective dystrophin gene in the boy. Which of the following people in the child's family is most likely to also have this disease?