When reading questions, be careful not to read too quickly. In this case, fast but inefficient reading will lead us to assume that it is asking about ...
If you sequence the dna of human as well as chimpanzees almost 99% of the sequence are similar showing they are phylogenetic related
Both parents must be carriers, which means they have the heterozygous gene (one uppercase letter & one lower case letter). They will still carry that mutated gene (because they have a lower case letter), and their offspring will have a 25% chance of getting a recessive disorder. The percentage is low but still possible.
