Essential Genetics 6th Edition by Daniel Hartl

Exercise 13

The recurrence risk of a genetic disorder is the probability that the next child born into a sibship will be affected, given that one or more previous children is affected. What is the recurrence risk for:
(a) A rare dominant trait in which one parent is affected?
(b) A rare recessive trait in which neither parent is affected?
(c) A rare recessive trait in which one parent is affected?