will be a symptomless carrier. When both parents carry the CF gene, there is a 25% chance (1 in 4) that their child will have Cystic Fibrosis. There is a 50-50 chance that the child will be a carrier like the parents. And there is a 25% chance that the baby will not have the gene -- not a carrier and not have the disease. The only way you can pass Cystic Fibrosis to your baby, is if both mother and father carry the gene. Yes they do. CF is caried in the CFTR gene.  In order for CF to be inherited, the altered gene must be carried by both parents.  If only one parent has it, the offsrping may end up a carrier but won't probably won't have the disease or show any symptoms but that offspring may pass on the CFTR gene to his/her own offspring. Comments on this question: In cystic fibrosis, a defective gene alters a protein that regulates the normal movement of salt (sodium chloride) in and out of cells. This results in thick, sticky secretions in the respiratory and digestive tracts, as well as in the reproductive system. It also causes increased salt in sweat. The affected gene, which is inherited from a child's parents, is a recessive gene. With recessive genes, children need to inherit two copies of the gene, one from each parent, in order to have the disease. If children inherit only one copy, they won't develop cystic fibrosis, but will