Question

Use a Punnett square constructed for the stated situation to answer the associated question.

In order to have sickle cell anemia, one needs to inherit two sickle cell anemia genes. In order to be a carrier of sickle cell anemia, one needs to inherit one sickle cell anemia gene and one normal gene. Consider the genetic possibilities for a child of parents who are both carriers of sickle cell anemia. What is the probability that the child will neither have sickle cell anemia nor be a carrier of sickle cell anemia?