As you can see from the image presented below when parents with AB Ss and AA ss genotypes cross we get three distinct phenotype groups.
Marked in red are the individuals whose A type blood we can determine from the saliva because they have at least one S allele.
Marked in light green are the individuals whose AB type of blood we can determine from the saliva too.
And marked in orange are the individuals that are homozygous recessive for the s allele, and we could not determine their blood type from their saliva.
Marked in red are the individuals whose A type blood we can determine from the saliva because they have at least one S allele.
Marked in light green are the individuals whose AB type of blood we can determine from the saliva too.
And marked in orange are the individuals that are homozygous recessive for the s allele, and we could not determine their blood type from their saliva.