Answer :
The children's father must also carry the recessive allele. Recessive alleles only determine characteristics when a child inherits a copy from each parent.
Answer:
The correct answer would be "The children's father must also carry the recessive allele".
Cystic fibrosis is an autosomal recessive disorder. Thus, a person must homozygous recessive in order to produce a phenotype.
Let C and c be the allele of the gene responsible for the disease. C is the dominant allele which codes for normal physiology and c be the recessive allele which codes for the disease when present in homozygous condition.
The mother is the carrier of the diseases that means she is heterozygous (Cc) for the disease.
In order that her children would get the disease, the father must carry c allele. He can be Cc or cc.
