Two phenotypically normal individuals have an affected child. What can we conclude about the parents?
(1) they both carried the diesease allele
(2) they are not the parents of the child
(3) they are affected
(4) no conclusions can be drawn
(1) Read Page 88, Figure 5.14 [b], XII NCERT
This means that the disease is caused by a recessive allele and both parents must have the recessive allele.