Person whose father is colourblind marries a lady whose mother is daughter of a colourblind man. Their children will be

Options

A. All normal
B. All colour blind
C. All sons colour blind
D. Some sons normal and some colour blind

Explanation

To solve the problem of determining the potential color vision of the children from a colorblind father and a carrier mother, we can follow these steps:

### Step 1: Understand the Genetics of Colorblindness
Colorblindness 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 will express colorblindness if his single X chromosome carries the colorblind allele (X^c). A female must have both X chromosomes carrying the colorblind allele (X^cX^c) to express colorblindness; if she has one normal allele (X^C), she will be a carrier (X^C X^c).

### Step 2: Determine the Genotype of the Father
The father is colorblind, which means his genotype is X^cY.

### Step 3: Determine the Genotype of the Mother
The mother is the daughter of a colorblind man. Since her father is colorblind (X^cY), her mother must have at least one normal X chromosome (X^C). Therefore, the mother’s genotype can be inferred as X^C X^c (carrier).

### Step 4: Set Up a Punnett Square
Now, we can set up a Punnett square to determine the possible genotypes of their children. The father's alleles (X^cY) and the mother's alleles (X^C X^c) will be used in the Punnett square.

```
X^C X^c
----------------
X^c | X^C X^c | X^c Y |
----------------
Y | X^C Y | Y |
```

### Step 5: Analyze the Results
From the Punnett square, we can see the following possible genotypes for the children:
1. X^C X^c (female carrier)
2. X^c Y (colorblind male)
3. X^C Y (normal vision male)
4. Y (not applicable for females)

### Step 6: Conclusion
The possible phenotypes of the children are:
- Female children: 50% chance of being carriers (normal vision) and 0% chance of being colorblind.
- Male children: 50% chance of being colorblind and 50% chance of having normal vision.

### Final Answer
The children will be:
- 50% chance of being normal vision females (carriers)
- 25% chance of being colorblind males
- 25% chance of being normal vision males