Cystic fibrosis is a rare disease caused by homozygosity for arecessive allele, and characterized by a build-up of mucus in thelungs and difficulty breathing. A woman whose maternal uncle hadthe disease is trying to determine the probability she and herhusband could have an affected child. Her husband's sister died ofthe disease. Assuming the uncle and the sister are the only familymembers who had the disease, what is the chance that the couple'sfirst child will be affected? I'm getting 1/18, but chegg says1/64? Please verify it is 1/64 for the answer.
