Genes

[cvic1]

In humans, the allele for brown eyes (B) is dominant over the allele for blue (b). A couple, one of whom has brown eyes and the other blue, have four children, all with brown eyes. Is this proof that the brown-eyed parent is homozygous dominant? Why?

[alextemplet]

No because if the parent is heterozygous (Bb) then it's still possible for all four children to inherit the same dominant gene. Unlikely, but possible.

[MrMistery]

Update: the 1-gene, 2 alleles hypothesis for the inheritance of eye color is history