Hemophilia is a sex-linked disease. A normal man marries a woman whose father had it. What are the chances that they have 3 sons with hemophilia? a)1/8 b)1/4 c)3/8 d)1/2 Punnet square should have a XX* vs an XY, the "*"referring to the hemophilic gene. The actual answer explanation is that since only 2 of them will be sons, the odds that one of the sons gets it is 1/2, so it's therefore 1/2 * 1/2 * 1/2 to get A. I guessed A b/c it was the smallest, but I reasoned that hte odds of getting a son with hemophilia was 1/4 since you could also get daughters. With questions like these, how do I know to assume that difference? Where the getting the son assumption is 100% (rather than 50%) and getting a son with hemophilia is one of the two sons and not one out of the possible kids?