A woman of normal vision whose father was colourblind, marries a man of normal vision, whose father was also colourblind. The sons of this marriage would be :-

Options

A. All normal
B. All colourblind
C. 50% colourblind
D. 100% colourblind

Answer

To solve the problem, we need to analyze the genetic information given about the woman and the man in the marriage, focusing on the inheritance of colorblindness, which is an X-linked recessive trait.

### Step-by-Step Solution:

1. **Identify the Genetic Background of the Woman:**
- The woman has normal vision, but her father is colorblind. Since colorblindness is an X-linked recessive trait, the father must have the genotype X^cY (where X^c represents the colorblind allele).
- The woman must have received one X chromosome from her father (X^c) and one X chromosome from her mother. Since her mother has normal vision, she has at least one normal X chromosome (X). Therefore, the woman’s genotype is X^cX (she is a carrier of colorblindness).

2. **Identify the Genetic Background of the Man:**
- The man also has normal vision, but his father is colorblind. Similar to the woman, the father must have the genotype X^cY.
- The man must have received a normal X chromosome from his mother (since he has normal vision) and a Y chromosome from his father. Therefore, the man’s genotype is XY (normal vision).

3. **Determine the Possible Genotypes of Their Sons:**
- Sons inherit their X chromosome from their mother and their Y chromosome from their father.
- The mother (X^cX) can pass on either the normal X (X) or the colorblind X (X^c) to her sons.
- The father (XY) will always pass on the Y chromosome to his sons.

4. **Possible Combinations for Sons:**
- If the mother passes on her normal X chromosome (X), the son’s genotype will be XY (normal vision).
- If the mother passes on her colorblind X chromosome (X^c), the son’s genotype will be X^cY (colorblind).
- Therefore, the possible genotypes for the sons are:
- 50% chance of XY (normal vision)
- 50% chance of X^cY (colorblind)

5. **Conclusion:**
- The sons of this marriage would have a 50% chance of being colorblind and a 50% chance of having normal vision.

### Final Answer:
The sons of this marriage would be: 50% chance of colorblind (X^cY) and 50% chance of normal vision (XY).

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