Why do two lousy fathers have prostate cancer in TB? Considering the vast palette with which Troubled Blood is painted, it's no accident that two prominent fathers, Roy Phipps and Jonny Rokeby, both suffer from the same illness, prostate cancer. Roy also has the rare von Willebrand disease and the Athorns have Fragile X, so it's not like JKR has misplaced her copy of Black's Medical Dictionary. With all the maladies to choose from, why *that* one, and why give it to two fathers belatedly trying to make amends with their estranged children?