Pedigrees help geneticists understand how traits are inherited between generations. Red-green color blindness is a sex-linked disorder that is determined by a recessive allele on the X chromosome.If Brian has a son who is color-blind, what is known about the genotype of the son's mother?
Answer
A
She must have at least one allele for color blindness.
B
She must have two alleles for color blindness.
C
She cannot be homozygous recessive for the gene for color blindness.
D
She cannot be a heterozygous carrier of the gene for color blindness.