At one gene location on a human chromosome, a dominant allele controls whether you can curl the side of your tongue upward. People homozygous for the recessive allele cannot roll their tongue. At a different location, a dominant allele controls whether earlobes are attached or detached. These two gene pairs assort independently.

So, suppose a tongue-rolling woman with detached earlobes marries a man who has attached earlobes and can't roll his tongue. Their first child has attached earlobes and can't roll his tongue.

a. What are the genotypes of the mother, father, and child?

b. What is the probability that a second child will have detached earlobes and won't be a tongue roller?