One of the earliest models for the genetics of eye color was developed in 1907, and proposed a single-gene inheritance model, for which brown eye color is always dominant over blue eye color. Suppose that in the population, 25% of individuals are homozygous dominant (BB), 50% are heterozygous (Bb), and 25% are homozygous recessive (bb).

(a) Suppose that two parents have brown eyes. What is the probability that their first child has blue eyes?

(b) Does the probability change if it is now known that the paternal grandfather had blue eyes? Justify your answer.

(c) Given that their first child has brown eyes, what is the probability that their second child has blue eyes? Ignore the condition given in part (b).