If a brown-eyed man marries a blue-eyed woman and they have 10 children, all with brown eyes, what
would be the most likely genotype of the father? If the 11th child has blue eyes, what would you now say
about the father’s genotype?
To determine the most likely genotype of the father and understand how the eye color is inherited, we need to consider the basic principles of genetics and eye color inheritance.
In terms of eye color inheritance, it is generally believed that eye color is determined by multiple genes. However, for the purpose of simplicity, we will consider a simplified model that focuses on a single gene controlling eye color, where brown eye color is dominant (B) and blue eye color is recessive (b).
If the brown-eyed man and blue-eyed woman have 10 children, all with brown eyes, it suggests that the man is homozygous dominant (BB) for the gene controlling eye color. Since all the children have brown eyes, it means they received a dominant allele from the father (BB), since having just one dominant allele (Bb) would result in brown eyes.
Now, if the 11th child has blue eyes, this indicates that the father must have passed on a recessive allele (b) to that child. Eye color is determined by the combination of alleles inherited from both parents. Since the child has blue eyes (a recessive trait), it means their genotype must be homozygous recessive (bb). Therefore, the most likely genotype of the father would be heterozygous (Bb) because he had to pass on a recessive allele to the 11th child.
To summarize:
- If all 10 children have brown eyes, the most likely genotype of the father would be homozygous dominant (BB).
- If the 11th child has blue eyes, it suggests the father is heterozygous (Bb) because he passed on a recessive allele to the child with blue eyes.