X and Y Chromosomes

I'm posting this because I just thought it was so cool. I know about the whole XX - XY boy - girl thing but I didn't realize that one of my Xs came from my grandmother on my Dads side... cool.

Each person normally has one pair of sex chromosomes in each cell. Females have two X chromosomes, while males have one X and one Y chromosome. Both males and females retain one of their mother's X chromosomes, and females retain their second X chromosome from their father. Since the father retains his X chromosome from his mother, a human female has one X chromosome from her paternal grandmother, and one X chromosome from her mother.