Why might genetically identical twins have different phenotypes?
1 answer:
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Answer:
50%
Explanation:
This question involves a gene coding for eye color in humans. The allele for brown eyes (B) are dominant to blue eyes (b). This means that blue-eyed individual will possess genotype: bb.
According to this question, a blue-eyed man (bb) has children with a brown-eyed woman (B_) whose mother has blue eyes (bb). Since the mother of the brown-eyed woman has a blue eye, this means that the woman will be heterozygous for brown eye (Bb).
Hence, the parents in this question will cross as follows: blue eyed man (bb) × brown-eyed woman (Bb). The offspring/children will have the following genotypes (see attached punnet square); Bb, Bb, bb, bb.
Based on the question, 2/4 = 1/2 of the children will be heterozygous for the eye color trait. That is, ½ × 100 = 50%.
