A Young Couple Already Has Three Children and Is Expecting

Essay

A young couple already has three children and is expecting a fourth. Through a genetic test, the couple finds out that each of them is a carrier for cystic fibrosis. Upon counseling, they are informed that there is a 1 in 4 chance of their unborn child having cystic fibrosis and a 1 in 2 chance that he/she will be a carrier. Describe how the genetic counselor was able to determine these probabilities. The husband deduces that the child will be born with cystic fibrosis because the other 3 children do not have it. Explain why this reasoning is faulty. How would you handle the situation?