Final answer:
The most probable genotypes of Ralph's parents are X^H X^h (carrier of hemophilia) for the mother and X^N X^N (normal clotting factor genes) for the father.
Step-by-step explanation:
The most probable genotypes of Ralph's parents can be determined by understanding the inheritance pattern of hemophilia. Hemophilia A and B are both X-linked recessive disorders, meaning they are passed down on the X chromosome. Males have one X chromosome and one Y chromosome, while females have two X chromosomes.
Ralph has normal blood clotting, so he must have received a normal clotting factor gene from one of his parents. Since Ralph's two brothers and sister have hemophilia, we can conclude that their mother is a carrier of the hemophilia gene. This means that Ralph's mother has one normal clotting factor gene and one hemophilia gene on one of her X chromosomes.
Ralph's father, on the other hand, does not have hemophilia since none of his children have inherited the disease. Therefore, Ralph's father must have two normal clotting factor genes on his X chromosome.
Based on this information, the most probable genotypes of Ralph's parents are:
- Ralph's mother: X^H X^h (carrier of hemophilia)
- Ralph's father: X^N X^N (normal clotting factor genes)