In a marriage between a female "carrier" of red-green color blindness and a normal male, what proportion of their male progeny will have the trait?

In considering a marriage between a female carrier of red-green color blindness and a normal male, we start by understanding the genetics behind this trait. Red-green color blindness is an X-linked recessive trait, which means the gene responsible for the condition is located on the X chromosome.

The female carrier has one normal X chromosome and one affected X chromosome, which can be designated as X^N (normal) and X^c (color blind). The normal male has one X chromosome (X^N) and one Y chromosome (Y).

When a carrier female and a normal male have offspring, their daughters will inherit one X chromosome from each parent, while their sons will inherit their X chromosome from the mother and a Y chromosome from the father. The possible combinations for their male progeny are:

• From the mother: X^N or X^c

• From the father: Y

This results in two potential genotypes for their male offspring:

1. X^N Y (normal vision)

2. X^c Y (color blind)

Since the carrier mother can pass either X chromosome equally, there is a 50% chance that a son will inherit the affected chromosome (X^c), and a 50% chance he will