KR AFPhoenix, are you saying that the other half of the mares genes didnt have to be gray, and therefore make it possible for her to throw other colors?

Aficat I forgot I was on a board with mostly well-knowledgeable horse people. Try teaching a diverse high school Equine Science class the difference between Dun and Buckskin Sure, they get that theres a difference in color genes, but they argue and question when I say that so-and-so horse is buckskin, or so-and-so horse is Dun. Also, because A LOT of Buckskins look like Duns (at least to the untrained eye, especially due to countershading), they can be confused. I assumed people would fight me on the Dun issue because her dam was gray. I, for one, have never known a gray mare to produce a Dun foal.


Well, I'm only a college junior, so I still remember high school. I wish I had had a horse class in high school; the closest I got was going to an ag-centered charter school with an FFA team, and frankly I was more knowledgeable on horses than most of the teachers there. I've got a ton of the bookwork in my head, I just need to find more...sane horse people to learn the practical side of the industry. I've got a frosted buckskin and a palomino dun in my backyard, so dun/not dun is kind of personal to me :) .

Yes, a mare's genes are on paired chromosomes, which is where the homozygous and heterozygous status comes from. If your mare's dam was GG for the dominant grey (gray?) gene, every one of her eggs would have the grey factor, therefore all of her babies would be grey.

If she was heterozygous GX, she would be grey, but ~50% of her eggs would carry the grey gene when the chromosomes split to create the gametes (egg and sperm) and the other percentage would have the "not grey" gene. The babies without the grey gene would not be grey, and none of thier babies would be grey unless they're bred to another grey. HYPP, dun, and black work the same way.

Chestnut and HERDA are recessive genes, so they need EE homozygous genes to show up, but if the dam is EX, the mare wouldn't look chestnut/sorrel/whatever, but could pass that on and have chestnut babies with stallions that also pass on the chestnut gene.

/genetics 101 FTW!