The marriage was entered between a woman and a man with normal color vision. A boy with color blindness was born.

The marriage was entered between a woman and a man with normal color vision. A boy with color blindness was born. The gene for color blindness is known to be recessive and sex-linked. Determine the genotype of the parents and the child, as well as the possible genotypes and phenotypes of the children

The gene for color blindness is localized on the X chromosome – a recessive trait. Parents have normal vision, the father in the genotype has only one X chromosome (the sex of the father is determined by the X and Y chromosomes), which carries the gene for the dominant trait. But the mother has two X chromosomes. Since the born child was a boy suffering from color blindness, it means that he inherited a Y chromosome from his father, and an X chromosome with a recessive trait from his mother.

Conclusion: the genotypes of parents and children are as follows:

father                     mother

Х_АУ                       Х_АХа

Child

ХаУ