Biology for IGCSE & O level - Inheritance (Section 7 - No. 5)
If a woman has a colorblind son, and her husband has normal vision, what must be the woman's genotype, assuming that colorblindness is an X-linked recessive trait?
XBXB
XbXb
XBXb
XBY
Forklaring
She must be a carrier (XBXb) to have a colorblind son.