Homozygous Grey and "True Breeding Bay" Thoroughbred Stallions:

This is a topic that comes up regularly on the TB forums I read, and rather than create a new list everytime the subject arises, I decided to put the lists here for anyone to reference.

Homozygous Greys: Homozygous greys are horses that carry two copies of the grey gene, one from each parent, meaning that every single one of their foals will inherit a grey gene, and thus will be grey.

"True Breeding Bays:" The phrase "true breeding bay" is really a misnomer. What it refers to are horses who are homozygous for black (EE) and thus cannot sire a chestnut (ee) even when bred to one. Calling them true-breeding bays or homozygous blacks can be confusing because blacks, bay, browns, smoky blacks, buckskins, smoky creams, and greys can all be homozygous for black despite having other modifiers. I prefer to call them non-chestnut carriers. It's simpler and less confusing.