What is the probability that the first child of two heterozygous brown eyed parents will be blue eyed? if the first child is blue eyed what is the probability that the second child will be blue eyed?

Let the allele for brown eyes be 'B' and let the allele for blue eyes be 'b'. Therefore, crossing between two brown-eyed parents of heterozygous alleles would be: Bb X Bb which could produce:

1. BB

2. Bb

3. bB

4. bb

There are four possible outcomes, with only one outcome: 'bb' producing a child with blue eyes. Therefore, the probability of a blue-eyed child is 25%. This probability does not change for the second child.