Question

Women have sex chromosomes XX, and men have sex chromosomes XY. Which of a woman's grandparents could not be the source of any of the genes on either of her X chromosomes?

Answer 1

Answer: her grandpa could not have been the source of either of her XX chromosomes.

Explanation: A male is the sole provider of the Y chromosome whereas females only have two XX's and no Y's

Answer 2

Answer: The grand father could not be source of the woman XX chromosomes.

Explanation:

Female always have XX chromosomes and the male have XY chromosomes. A woman can only release X chromosome and a man can release either X or Y chromosomes. When a man release Y chromosomes and join to the female X chromosome, the offspring will be male but when a man release X chromosome, the offspring will be female.