Fun with Genetics

I first started to wonder about the genetics of cat coat colors and patterns around the time I adopted Calpurnia. My previous cats had been far more standard cats: tabbies, tuxedo cats, a dilute tortoiseshell. Calla’s coat is not only is a more exotic one, but has several combinations together. I had to find out what was possible or not possible to see on a cat.

It turned out to be relatively simple. Nature takes a few simple characteristics and combines them to produce the final coat, instead of having them preset and selected. Thus a small amount of genetic programming goes a long way.

Page Guide

Coat Color – page 2

Tabby and Agouti – page 3

Coat Modifiers – page 4

Albino and Colorpoint– page 5

White Spotting – page 6

Shaded and Smoke – page 7

22 Responses to Fun with Genetics

  1. Pingback: Agouti, or not Agouti | ThreeCatYard

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  4. Pingback: The Tabby Gene | ThreeCatYard

  5. Pingback: Cat Genetics 101 | ThreeCatYard

  6. minlit says:

    The new analysis page is great! You’ve put so much work into it! Well done. Super project.


  7. Dianda says:

    Oh my god! Kuddo’s to you! This is great!
    Is it alright if I put this link in my blogroll?


  8. Dianda says:

    Thank you! 🙂


  9. Star Wise says:

    Wow, your genetics information is great. I have a large furry cat, Shandy, and someone said he might have Maine Coone in him. I am sorry but when I began reading your pages on coat colour I became befuddled (probably because of being tired after a hard day at work). Would you say my kitty, Shandy, is tabby and white? You can see him on “Our Animal Companions” page of my site. Thank you


    • Oldcat says:

      Yes, Shandy is a tabby with white. The White Spotting gene is responsible for the white lying “over” the tabby pattern.
      It has a variable expression, though. For low levels this starts with white feet then moves to belly chest then face, then up the sides and around the neck. This is where Shandy is. Higher levels get to where only the top of the head and tail are non-white, then finally a completely white cat.

      I like the colored spot that still exists on the tummy, though.


      • Star Wise says:

        Thank you Oldcat ! Your cat showcase is very pleasing and all the examples beautiful. I didn’t know there were “cinnamon” cats. I have always thought about having a blue-cream cat. My twin sister used to sketch and colour in different cat breeds, while I, more interested in “girlie” things would list all the types and brands of my cosmetics


  10. Wonderful site! Many thanks. I do have a [few] question[s], although a bit complicated. First, I breed Maine Coons. I have a wide variety of colors, including solid white and shaded. I recently had a litter of six. The mother is solid white and the father is cream smoke shaded [possibly chinchilla, if that were recognized in Maine Coons]. The white mother is probably masking red or cream tabby or solid without white, and probably not carrying the Inhibitor gene. Of the six kittens, one is solid white. The other five, males and females, are cream silver or smoke, some probably shaded. I have been trying to determine the probability that the white kitten is masking the Inhibitor gene, with the theory [and hope] that the shaded/chinchilla father carries two rather than one Inhibitor gene. That is how I first learned about the wideband gene, which suggests that there is no way to determine whether the father carries one or two Inhibitor genes. Can you tell me if this is a correct assumption.

    Second question: I have also been trying to determine the cause of deafness in white cats. My theory, supported by some, is that the combination of the White gene and the Spotting gene is to blame. And, in a solid white cat, when the Spotting gene falls over the eye, the eye is blue. When it falls over the ear, the ear is deaf. [There are human conditions in which the lack of pigmentation is related to deafness.] Do you have any thoughts on this?

    Many thanks for your time and consideration!


    • Oldcat says:

      Assuming Mom has no “I” genes, then if Dad had two genes all kittens would have one, which is what you see. If Dad had one “I”, then you’d expect half the kittens to be normal. So, the chance that with 50 percent per kitten you came up with all smokes is .5 multiplied 5 times, or one chance in 32 – about 3 percent. So you can’t be 100 percent confident that the all-white kitten has “I” but if you laid out all 128 choices for 6 kittens in both cases (double I dad and single I dad), then eliminated those where a visible kitten was non I, you’d find only one case out of 66 remaining choices where the white kitten has no inhibitor. Pretty good odds!

      On the second question, I’m pretty sure that dominant white OR high levels of white spotting up to the ear can cause deafness in cats, because of the link between pigment and ear development as you said. It has been a while, but I think that the Albino solid white variants (pink eye and blue eyed albino) don’t link to deafness the same way.

      I’d think that if a combination of both were required, it would be relatively easy to show it by introducing one gene or the other into a line of cats without either and showing no deafness results.


  11. Many thanks; this is so much fun!


  12. Star Wise says:

    Hi oldcat, I would like to ask you what you think about the genetics of Venus, the “chimera” cat, as on my Blog. Link is below.

    Also, did you ever get an email from me with a poem tribute for Gus? I tried commenting on the relevant post but Word Press wouldn’t let the Comment go through back then, for who knows what reason, so I used your Contact Me page. 🙂


  13. Star Wise says:

    Here is my poem tribute for Gus. I couldn’t post it on the “Farewell to Gus” thread, but you can move it to that thread if you like.

    Thank you Gus
    For transforming us
    A beautiful boy always
    You never ceased to amaze
    We loved your sweet kind face
    Your gorgeous black & white coat
    And magnificent deportment something to gloat
    Wise and special friend
    Your love never ends
    The Body goes, but the Spirit flows,
    Thank you for being with Us
    Wonderful Spirit called Gus


  14. Thank you for the accuracy and detail you have shared in your Fun with Genetics section. Cat genetics is an area that is not widely discussed but it should be.


  15. Chris Howard says:

    I believe we just had a chimera kitten born. Mother is a dilute tortie with white feet. She had 3 dilute kittens, a tabby, a tortie, and a light gray, almost a fog color. 4th kitten is a tabby with white. The front half is normal dark, almost black tabby, the back half is dilute tabby, a light gray. I’ve never seen such a cat.


    • Oldcat says:

      This might be a fever coat. If mother gets sick, it can affect the coat in interesting ways. Eventually the kitten fir is lost and the coat is normal.


  16. Katie M says:

    I have two unrelated cats.

    Charlie is all black, although I can see faint tabby stripes in the right light. He also “rusts” in the sun. The strange thing about him is that the skin underneath his fur appears to be white, and the insides of his ears and mouth are very pale. I’ve had him checked out, so I know it’s not a health problem. I can’t seem to find anything on this.

    Selene is a grey tabby. She seems to have every shade of grey possible, with the lightest areas appearing either white or extremely light grey depending on lighting conditions. I even named her after an ancient moon goddess because she’s basically got all of the moon’s colors.


    • Oldcat says:

      Normal cat coloring is temperature sensitive and will be lighter near the skin. On black cats this will be a pale grey, not pink as skin is under white fur. Do a google image search on “shaved tuxedo cat” for a view of this.

      There is also a gene that blanks out the color near the skin. This produces what is called a ‘smoke’ or ‘shaded’ cat, depending on other factors. Each hair is white at the base. I don’t know if the skin is correspondingly paler to match this, but skin color does follow hair color normally.

      The rusting and ghost tabby stripes are normal. All solid cats are ‘black on black’ and the difference can often be seen.

      As for tabbies, if the mottled pattern on the agouti hairs as they overlap can produce any number of apparent colors. A grey tabby avoids having the undercolor be orange so the effect is different to the eye.


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