A colour blind man marries a daughter of another colour blind man whose wife had a normal nenotype . In their progeny

Options

A. All the children will be colour blind
B. All therir sons are colour blind
C. None of the daughter would be colour blind
D. Half of their sons and half of their diaughters would be colour blind.

Answer

To solve the problem of color blindness inheritance in the given scenario, we will follow these steps:

### Step 1: Understand the Genetic Basis of Color Blindness
Color blindness is a sex-linked recessive trait, which means it is carried on the X chromosome. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). A male with a color blindness allele on his X chromosome will express color blindness, while a female must have the allele on both of her X chromosomes to express the trait.

### Step 2: Determine the Genotypes of the Parents
- The colorblind man has the genotype **X^cY**, where **X^c** represents the X chromosome with the color blindness allele.
- The daughter of another colorblind man (whose wife has a normal genotype) must have received one normal X chromosome from her mother and one colorblind X chromosome from her father. Therefore, her genotype is **X^cX**.

### Step 3: Set Up the Punnett Square
We will cross the genotypes of the colorblind man (X^cY) and his daughter (X^cX):

| | X^c (from daughter) | X (from daughter) |
|---------|----------------------|--------------------|
| X^c (from father) | X^cX^c (colorblind daughter) | X^cX (normal daughter) |
| Y (from father) | X^cY (colorblind son) | XY (normal son) |

### Step 4: Analyze the Offspring
From the Punnett square, we can see the possible offspring:
- **Daughters**:
- X^cX^c (colorblind)
- X^cX (normal)
- **Sons**:
- X^cY (colorblind)
- XY (normal)

### Step 5: Conclusion
From the analysis, we find that:
- 50% of the sons will be colorblind (X^cY).
- 50% of the daughters will be colorblind (X^cX^c).

Thus, the correct answer is that half of their sons and half of their daughters would be colorblind.

### Final Answer
**Option D: Half of their sons and half of their daughters would be colorblind.**

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