Chiilaa is correct. With the colors of the sire and dam we have available, the options are sorrel (not likely and only a chance if the perch stud is heterozygous for black, which is rare), black, or bay, each with a 50% chance of going gray.
Gray is a modifier and it is dominant. It doesn't hide. The mare is heterozygous for it since one parent was a non-gray, therefore, she has a 50% chance of passing on the gene. If the foal were to be born with even one copy of the gray gene, then it would be gray.
While there is a slight possiblity of the foal being smoky black or buckskin (only if the dam is either a buckskin or a palomino underneath her gray), it is unlikely.
Hmm, Idk if this helps at all, but the mare was registered as a red roan overo paint as a yearling, then turned grey. This is a photo of her dad, and EVERY one on his side going back three generations is listed as sorrel overo. Most of the horses on her mom's side are listed as Tailwind bred, but only say QH underneath, no colors. The guy with the percheron only breeds for black.
Yep, that means the only options for base colors are either black or bay, depending on whether the mare carries agouti or not.
Whether or not she's actually a roan or whether they listed her as roan due to her markings makes me wonder though. I don't know a ton about the paint patterns, but her sire looks like he's carrying sabino too, which can cause pretty extensive roaning.
If she carries the actual roan gene, then she also has a 50% chance of throwing a bay/blue roan.
I have pics of her as a baby, and she was roan. I'm not sure if she's still considered roan or not. In the winter her grey fades completely and she looks pure white, with only a litle grey in her mane and tail. Isn't changing color drastically a trait of roan coloring? She looks like a completely different horse in summer and winter.