Blue eye colour in human in recessive to brown eye colour. The expected children of a marriage between a blue-eyed woman and a brown-eyed male who had a blue-eyed mother are likely to be in the ratio of:
One blue-eyed and one brown-eyed
The recessive character is expressed only in homozygous condition thus blue-eyed woman will have bb genotype, while brown-eyed man may have BB or Bb genotype. But the man had a blue-eyed mother so, he will have Bb genotype. It can be explained as follows: