Problem 418. Blood test?

Assuming: the genetic makeup (genotype) of a child is coded as a pair with two components, combining half genotype of one parent with half from the other parent, the possibilities are:

• A+A
• A+B
• A+O
• B+B
• B+O
• O+O

The corresponding blood group of the child will be observed (phenotype) to be A, AB, A, B, B, and O respectively. Given either genotype (3 characters, such as 'A+O') or phenotype (1 or 2 characters, such as 'A' or 'AB') of a child, a putative father, and a putative mother, determine 'maybe' or 'unlikely'.