Feline fur genetics explained by expurrts to a curious cat pawrent, after observing her cat's unique coat color patterns.

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Ayala Sorotsky • Writer and Editor
Mar 3, 2026 3:00 PM EST

We're constantly fascinated by cats, and with good reasons it seems.

Cats never fail to tickle our curiosity, and we truly believe they are one of the more interesting creatures to walk on this Earth. You'd think that by this point, after thousands of years we share our lives with cats, we would know everything there is to know about them. That's a false sense of security cats probably create on purrpose. There's always something new to learn about cats!

Though you've seen all colors of cats' eyes? Think again, because a cat with "kintsugi pottery" eyes exists. Did you think the domestic cat is the only small cat you're going to know for life? Wrong again, there are plethora of wonderful wildcats that Mother Nature blessed this planet with. And let's not forget the absolutely stunning feline fur colors some cats rock.

Speaking of these beautiful cat coats - there's always something to learn about how they're made. And that' exacly what one pawrent to an ameowzing black-ish cat asked, and the answer from the online feline family soon came. Ready to learn even more about our favorite four-legged friends? Let's go!

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  • 01
    Is my cat a black tabby or a black cat? Shes about 11 years old, found as a stray.
    via Flimsy-Lengthiness48
  • 02
    Cheezburger Image 10610784256
    via Flimsy-Lengthiness48
  • 03
    I'm curious because the striping I see in the first picture only shows up in bright light but she doesn't sun herself much ( prefers my heating vents) so I don't think it's sun bleaching.
    via Flimsy-Lengthiness48
  • 04
    Cheezburger Image 10610784768
    via Flimsy-Lengthiness48
  • 05
    Also she has these singular white hairs speckled throughout her coat and a very small patch in- between her back legs. All four paws have black skin. The
    via Flimsy-Lengthiness48
  • 06
    Cheezburger Image 10610786560
    via Flimsy-Lengthiness48
  • 07
    vet didn't make note of any irregularlarites during her spay so I think she has a basic XX chromosome.
    via Flimsy-Lengthiness48
  • 08
    lipstick_spit solid black. fun fact: all cats are naturally. tabbies as in, their fur and genetic build is made to be a tabby. the difference is that if a (typical, tabby) cat has two copies of the recessive "solid" gene, then
    via lipstick_spit
  • 09
    they overproduce eumelanin and turn black! the solid gene is a masking gene that turns the "background" (agouti) hair between the stripes black as well, like a kind of overflow of the stripes. genetically, this is
    via lipstick_spit
  • 10
    caused by a mutation on the agouti signaling protein to... stop signaling agouti. lol. however, you still have the pattern that the cat was "meant" to be written in the skin. think of the clear patterns of melanistic jaguars, for example!
    via lipstick_spit
  • 11
    (though cats and jaguars have their respective mutations on separate genes).
    via lipstick_spit
  • 12
    this is why you will often see phantom markings in black cats, and why black smoke cats will get a pseudo-tabby pattern along their pelt―
    via lipstick_spit
  • 13
    theyre following the genetic pattern already laid out, that is just hidden from us! it is also why every red cat is visually a tabby. theyre not producing eumelanin, because they are red, and so the masking effect of the solid gene doesnt end up strong enough to cover the stripes.
    via lipstick_spit
  • 14
    the white hairs are normal. just little malfunctions of melanin production. the white on the belly might be. low white spotting or a locket (which is also a small malfunction of melanin production).
    via lipstick_spit
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    Cheezburger Image 10610785536
    via Flimsy-Lengthiness48

  • The delightfully nerdy truth that this expurrt is basically saying that all cats start as tabbies. The default feline setting is stripes. Genetically, their fur pattern is built on something called the agouti system, which creates that classic light-and-dark banding along individual hairs. Now, when a cat inherits two copies of the recessive “solid” gene, things get dramatic. This gene essentially tells the agouti signaling protein to hush, which leads to an overproduction of eumelanin (dark pigment). The result is a black cat.

    But plot twist: the original tabby pattern is still there. It’s just hidden under all that extra pigment, like a striped blueprint beneath a dark paint job. That’s why some black cats show “phantom” tabby markings in certain lighting - the stripes never left.

    This also explains why red cats are always visibly tabby. Red pigment doesn’t produce the same eumelanin overload, so the stripes stay on display. As for random white hairs or little belly patches? Those are minor melanin production hiccups - tiny pigment glitches that make each cat uniquely customized.

  • 16
    Cheezburger Image 10610786304
    via Flimsy-Lengthiness48
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    Flimsy-Lengthiness48 OP Thank you for the detailed answer! I was originally asking because I had read somewhere that a solid color female cat was actually rare because they require a homozygous 'solid' gene, whereas a black tabby was more along the lines of black panther. Still patterned just with more melanin.
    via Flimsy-Lengthiness48
  • 18
    That, plus I can only see my cat's patterns on her chest, forelegs, right flank and tail made me think she was a black tabby.
    via Flimsy-Lengthiness48
  • 19
    lipstick_spit it seems like youre maybe getting a few things mixed up here!
    via lipstick_spit
  • 20
    the first of which is that a black tabby is probably what youre thinking of as a "brown" tabby. these are black cats, genetically, because that is the color of eumelanin they are producing. you can determine this visually by the stripes, because there is no agouti banding to muddle it visually. the darkest black tabby
    via lipstick_spit
  • 21
    youre going to see would be a sheeted marbled bengal... anything more black than that (with no agouti banding, and no countershading giving the cat eyeliner, a lighter muzzle, a light belly and paws, and a light undertail, as seen in this black tabby) is not a tabby at all. i suspect you are thinking of said ghost striping, which is
    via lipstick_spit
  • 22
    often most visually striking in smokes and kittens. the solid gene is fully recessive to tabby, and requires two copies of the solid allele to present as solid... even if there are markings peeking through.
    via lipstick_spit

  • Ah, black smoke cats - the mysterious, gothic royalty of the cat world. From afar, they look like sleek, solid black cats straight out of a noir movie. Up close? Surprise! Each hair is a mini magic trick: dark tips overlaying silvery-white bases.

    This happens because of the “incomplete masking” effect of the solid (or melanistic) gene. Essentially, the cat’s default tabby blueprint is still hiding underneath all that dark pigment, but instead of fully covering the lighter base, the black pigment only dominates the tip. The result is a smoky, ghostly shimmer as the cat moves, like it’s fading in and out of existence - perfect for dramatic napping in sunbeams or stalking shadows. You might even catch faint tabby stripes showing through, especially around the legs, tail, or face. This effect is similar to the “phantom tabby” phenomenon seen in other black cats, but taken to an elegant extreme.

    In short, black smoke cats are genetic art: tabby by blueprint, black by gene, and smoky by sheer optical wizardry.

  • 23
    the second of which is where sx comes into play with cat colors. there are two "bases" for cat color: red-based (this is red and cream) and black-based (this is black, chocolate, cinnamon, and all of their dilutes). the mutation for red- based is on the x-chromosome. if a cat has one x-chromosome (males, typically), this is easy!
    via lipstick_spit
  • 24
    they either get an x-chromosome from their mother with the red mutation, making them red-based, or they dont... making them black- based. it gets a little more complicated with two x-chromosomes. they get one from their father, and one from their mother. if those two X-
    via lipstick_spit
  • 25
    chromosomes are both red-based, the female cat is red. if both are black-based, the female cat is black. but, they also have the additional option of receiving one red-based x- chromosome and one black-based x- chromosome. this is where the tortoiseshell pattern comes in! if a cat is heterozygous for the red mutation, they present both colors (due to lyonization, which is a bit much to get into here).
    via lipstick_spit
  • 26
    this is just the base color, every other modification is built upon this and is not sox- linked. this includes solid vs agouti, tabby pattern, dilute vs dense, colorpoint, corin mutations, the inhibitor mutation... literally
    via lipstick_spit
  • 27
    everything else is separate from the red vs black base color determined by the x-chromosome. so, a female cat having the black base color (including being a black tabby, seal point, golden chinchilla, etc) is only less common than
    via lipstick_spit
  • 28
    a male cat having the black base color because she had three "base color" options (red, black, and tortoiseshell) while a male only had two (red, black). so its more of a 33-33-33 distribution than a 50-50 distribution... in a perfect population where each color is equally present.
    via lipstick_spit
  • 29
    hope this was clear. its kind of a crash course, so feel free to ask questions.
    via lipstick_spit

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