Blue eyed genes

Could anyone here explain to me how blue eyes get passed on? My stallion when bred previously to solid mares threw a single blue eye on 2 foals and double blue eyes on 1. Does this mean all his foals will have at least one blue eye? Are two blue eyed parents a guarantee for blues? I was just never sure on how exactly they get passed on.

Blues are caused by double dilutes (cremellos, perlinos and smokey creams) and in those instances, if you breed two double dilutes together you'll always get a double dliute foal, so always two blue eyes.

But that's not what you're talking about. Blues are also caused by frame and splash. And there is no way to know if the foals will get one, two, or no blue eyes. Luck of the draw if you will. One of my stallions has a blue eye and I've had 3 foals from him, only one has a blue eye (and it's the opposite eye).

To my knowledge, there has been very little research to date about blue eyes in horses, so luck of the draw is probably the best answer.

Our bay tobiano mare has two blue eyes, but neither recent generations nor her offspring have had any blue eyed horses.

^

If she's tobiano with blue eyes, it's because the splash (most likely) or frame gene is hiding. Splash is the pattern most likely to cause blue eyes, and it's often hidden in other patterns. My Paint filly came from two seemingly tobiano parents, but she's obviously got splash from her partial blue eye and splash face marking but it would have been easy for her to hide it because she's got so much white.

Breeding splash to splash would be your best possible chance of getting a blue eyed foal, regardless if the parents have blue eyes or not, though I have definitely seen a prevalence of blue eyed foals born to blue eyed parents. And it's still a complete luck of the draw, but a better chance then breeding a solid dark eyed chestnut to a solid dark eyed bay.