Cat eye genetics?

  • Can cats have different eye colors from their parents? I know that if a cat has the white dominant or the white spotting gene that it can cause them to have blue eyes, even if you can't see the white gene in effect.

    But what about other cat colors of eyes? I am having trouble finding information on how cat eyes work. Which are recessive and which are dominant? Can two yellow eyed cats give birth to a green eyed cat? I really want to know more.

  • The "answer" is that we (as in, humans) don't really know how cat eye genetics fully work. Two yellow eyed cats could probably have a green eyed kitten, but we don't know the basis behind it, so we leave the parts we don't know up to the RPer's choice. This is why for many litters the eye options will just say "any realistic eye color" or "any realistic eye color except blue". There are probably many genes controlling eye color, but we don't know which ones they are or how they are inherited.

    There are a few things we do know:

    - In general, cats that aren't white and don't have white markings, cannot have blue eyes. (There are some exceptions to this which I will mention later)

    - Cats that are all white can have any eye color, including blue, and can also have one blue eye and one other color eye. However, blue eyed white cats have a 70% chance of being deaf from birth, and white cats with one blue eye have a 70% chance of being half deaf on the blue eye side.

    - Cats with white markings can have blue eyes. They are more likely to have blue eyes the more white, and especially the more white facial marking, they have. Cats with only a bit of white usually won't have blue eyes but it has been known to happen occasionally. There's no deafness risk with white marking induced blue eyes. According to this article there may be a recessive gene for blue eyes that only affects white-marked cats.

    - Point cats (the Siamese pattern, but it's found in other breeds too) always have blue eyes. They also lack the reflective layer that most cats have at the back of their eyes, meaning their pupils will not reflect in the dark.

    - Blue-eyed albino cats (which are VERY rare) have pale blue, lavender, or pinkish-blue eyes. They also don't have the reflective eye layer, and have a lot of vision problems due to the lack of pigment.

    - Pink-eyed albino cats (even rarer) have pale pink eyes, no reflective layer, and even worse vision problems than blue-eyed albinos. This mutation formerly wasn't found in domestic cats (not that that stopped a lot of people from RPing pink-eyed albino cats on this site lmao), but it's occurred in Bengals due to being introduced from Asian Leopard Cats.

    - Mink cats (Tonkinese pattern, but also found in other breeds) have aqua/blue-green eyes.

    - Sepia cats (Burmese pattern, but also found in other breeds) have eye colors in the range of gold to yellow to green. Pedigree Burmeses, specifically, have been selectively bred to always have golden eyes, but that's because of selective breeding over many generations, not because of the sepia mutation.

    - The Ojos Azules mutation, which is very rare and going extinct since the breeding project has stopped, causes blue eyes without white markings. Unfortunately it is also homozygous lethal (meaning cats with 1 copy of the gene have blue eyes but cats with 2 copies are born dead).

    - The Topaz mutation can cause blue eyes, odd eyes (1 blue, 1 other color), or even black eyes, with either no white, or really weird white markings in patterns that white markings don't normally happen in. It's still pretty rare as it was only discovered recently. It's incomplete dominant, with homozygous cats having an increased risk of deafness. Topaz blue- or black-eyed cats also have no reflective layer at the back of their eyes.

    - The Altai mutation causes blue eyes or odd eyes when heterozygous, and deafness with blue eyes and high white markings (unrelated to the normal white marking gene) when homozygous.

    - Many breeds have a specific required eye color. However, (except for point/mink/sepia pattern breeds) this has been achieved by selectively breeding for that eye color over many generations, so we don't know what specific genes are involved.

    Want your characters' kids to have realistic fur colors? Check out the Genetics Center!
    Cats, lions, dogs, horses, rats, parrots - whatever the species is, there's probably a geneticist who can do the litter. We can also do genetics for realistic hybrid litters (check the list of realistic pairings linked in the sticky at the top of the board).
    If you want more options for a litter, just let us know!