I've been reading Kateri Tekakwitha: Mohawk Maiden (Vision Books) aloud to the kids. First Son, when hearing the child Kateri would dream of a Blessed Mary who looked like a Mohawk, said he usually imagined Mary as white.
I explained that Mary was probably darker than we are because the Hebrew people who lived in Nazareth and Jerusalem at that time were darker.
First Daughter replied, "Mary was darker on the outside, but she was whiter on the inside because her soul was cleaner. She never sinned."