I don't see your point. What does someone having green or blue eyes have have to do with me being a light eyes. If your light-eyed dad had say blue eyes and your mother had green isnt it feasible you'd have either one? Or perhaps both of your parents had blue but your grandmother had green couldn't you have green? Is there a genetic Wob on eye color I missed?
Evi had yellow eyes both her sons had blue.
I'm not sure which of Jasnah's parents she inherited her violet eyes from but I doubt it was Gavilar. And if it was Gavilar then how come Dalinar has blue?
It seems entirely possible that Shallan and her mother could have different eye color.