Problem 3: Unfortunately Punnett Squares are not always for finding out the best parts about parenting. They are often, as you will see in the next few lessons, often used to determine the probability of a disease being passed on to a child. We'll have you try one and see what that looks like. One such disease is Cystic Fibrosis. Let's assume both parents are heterozygous for Cystic Fibrosis. That means both parents carry the recessive gene for the disease, but because of the dominant genes they have, they don't have it. However, they want to know if they try to have a child, what the chances of the child would be for having Cystic Fibrosis?​