Carrier testing is a type of genetic test that helps determine if a person carries a gene for a specific inherited condition, even if they do not show any symptoms. This testing is particularly useful for conditions like cystic fibrosis or sickle cell disease, where both parents need to be carriers for their child to be affected. If both parents are found to be carriers of the same genetic condition, they have a 25% chance of having a child with that condition. Carrier testing can guide family planning decisions and inform individuals about their genetic risks and options for prenatal testing or in vitro fertilization.