Brown eyes are dominant over blue eyes. Suppose that two brown-eyed parents gave birth to a blue-eyed child. It may be inferred that

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Quizplus · Accepted Answer

Since brown eyes are dominant over blue eyes, a child can only have blue eyes if they inherit two recessive alleles for eye color. Therefore, both the mother and father must be heterozygous for brown/blue eyes, meaning they each have one dominant brown allele and one recessive blue allele. When they both pass down their recessive blue allele to their child, the child ends up with two recessive alleles for eye color, resulting in blue eyes. It is possible for two brown-eyed parents who are carriers of the recessive blue allele to have a blue-eyed child.

Brown Eyes Are Dominant Over Blue Eyes