Chapter 4, Problem 17QP

Analysis of X-Linked Dominant and Recessive Traits

A young boy is color-blind. His one brother and five sisters are not. The boy has three maternal uncles and four maternal aunts. None of his uncles’ children or grandchildren is color-blind. One of the maternal aunts married a color-blind man, and half of her children, both male and female, are color-blind. The other aunts married men who have normal color vision. All their daughters have normal vision, but half of their sons are color-blind.

1. a. Which of the boy’s four grandparents transmitted the gene for color blindness?
2. b. Are any of the boy’s aunts or uncles color-blind?
3. c. Is either of the boy’s parents color-blind?