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A male is colorblind, and his wife has normal vision. What percent chance do the sons have of being colorblind?

a) 0%
b) 25%
c) 50%
d) 100%

User Ajay Mehta
by
8.2k points

1 Answer

3 votes

Final answer:

Sons have a 0% chance of inheriting colorblindness from a colorblind father and a mother with normal vision, assuming the mother is not a carrier of the colorblind allele.

Step-by-step explanation:

When considering the chance that a son will be colorblind given that his father is colorblind and his mother has normal vision, it's important to recognize that colorblindness is a sex-linked trait specifically linked to the X chromosome. Since the question states that the mother has normal vision and does not specify that she is a carrier, we assume that she has two normal vision alleles (XX).

A male inherits the Y chromosome from his father and an X chromosome from his mother. Considering the father is colorblind, he has a colorblindness allele on his X chromosome (Xc). However, since males only inherit the Y chromosome from their fathers, the father's Xc allele is not passed down to his sons, it's passed down to his daughters. Consequently, the sons would only inherit the X chromosome from the mother. If we assume that the mother has two normal alleles (XX), the sons will have normal vision given that they would inherit the normal vision X from the mother and a Y from the father (XY), resulting in no chance of being colorblind.

Therefore, the sons have a 0% chance of being colorblind in this scenario, as they cannot inherit the X chromosome with the colorblind allele from their colorblind father.

User Dave Babbitt
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8.1k points
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