need question answered

Extra Credit Question for Saturday. This is the third, and final, extra credit question in this series. If you participate in this optional exercise, express you answer in a short paragraph. You have one chance to enter in your answer. After 3 a.m.(EST) Sunday morning it will no longer be available. The question is as follows.

Suppose that Max Stone marries a woman who has no history of this trait in her family at all. We do not expect any offspring of this union to have the trait. The expected probability is zero. This is true even though Max’s brother Jim Stone has the trait, and one of his great-grandfathers (Adam Fox) in the maternal line of descent also had the trait. Explain how we can infer that the probability is zero from the pedigree.