Question

Two normal people have a colorblind son.What is the genotype of the dad?What is the genotype of the mom?What is the genotype ratio among their children?What is the phenotype ratio among their children?

Answer 1

Given that the parents are not colorblind, but the son is, this means the mother must be a carrier because only females can be carriers for colorblindness.

This means that:

1. The genotype of the dad is XAY

2. The genotype of the mom is XAXa

Let's make a Punnett's square:

This means that the ratios would be as follows:

3. Genotype ratios:

25% XAXA

25% XAY

25% XAXa

25% XaY

4. Phenotype ratios:

25% Normal female

25% Normal male

25% Carrier female with normal vision

25% Colorblind male