The homozygous condition HbsHbsresults in sickle cell anaemia whereas HbAHbs has the sickling trait. What is the probability that a couple with the sickling...

If both parents have the sickling trait, they each carry one copy of the sickle cell gene (HbS) and one copy of the normal hemoglobin gene (HbA). When they have children, each parent randomly passes on one of their two copies of the hemoglobin gene to their offspring. There are four possible combinations of genes that their children can inherit from the parents: HbA/HbA (normal), HbA/HbS (sickle trait), HbS/HbA (sickle trait), and HbS/HbS (sickle cell anemia). The probability of having a normal child is therefore 1/4, as only one out of the four possible gene combinations will result in a normal child (HbA/HbA).