Orange cats are disproportionately male because the coat-color trait is linked to the X chromosome. A male cat typically has one X chromosome, so one orange-associated variant can be enough for an orange coat. A female typically has two X chromosomes and generally needs the variant on both to be entirely orange. Females can be orange, though, and one orange-associated variant paired with a non-orange one can produce tortoiseshell or calico patches.
Why are orange cats almost always male?
The orange trait is X-linked: the relevant genetic variant is on the X chromosome. Most male cats have one X chromosome and one Y chromosome, so they need only one orange-associated variant on their X to express the trait. Most female cats have two X chromosomes; to be entirely orange, they generally need the orange-associated variant on both.
This makes orange coats more common in males, not exclusive to them. Female cats can be fully orange, and coat color alone cannot reliably establish a cat’s sex. The official reports of the 2025 studies do not provide a population-representative estimate of what share of orange cats are male.
Why do calico and tortoiseshell cats usually have patches?
A female with an orange-associated variant on one X chromosome and a non-orange variant on the other can have both orange and dark fur. Early in development, different cells randomly inactivate one of their two X chromosomes. As those cells multiply, descendants retain the same active X, creating patches of different colors. Hiroyuki Sasaki, lead author of the Kyushu University study, described the patches as forming because “early in development, one X chromosome in each cell is randomly switched off.”
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Calico cats also have white areas, but those involve additional coat-pattern genetics; white is not produced by the orange variant alone. Tabby striping is another coat pattern and should not be confused with the sex-linked basis of orange coloration.
What gene makes orange cats orange?
Two independent research teams reported in Current Biology on May 15, 2025, that the orange trait is associated with a deletion involving ARHGAP36, a gene on the X chromosome. The Stanford-led study identified a 5-kilobase deletion linked to ectopic, melanocyte-specific expression of the gene. Its institutional report says the team narrowed its X-chromosome search from 51 candidate variants to three before identifying the deletion as the likely regulatory variant. Stanford’s account of the study describes the variant-screening work and the expression finding.
The Kyushu University team independently associated a deletion in the X-linked ARHGAP36 locus with orange coloration. Its press release reports an initial DNA analysis of 18 cats—10 orange and eight non-orange—followed by finding the shared deletion in 49 additional cats. Those are study sample counts, not an estimate of the proportion of orange cats that are male. The team also compared gene activity in orange and dark patches of calico tissue. Kyushu University’s report summarizes its sample analysis and findings.
How does the deletion affect coat color?
The findings point to altered ARHGAP36 expression in pigment-producing cells, with downstream effects on pigment-production pathways. They do not mean the deletion simply makes orange pigment directly. Stanford describes the gene’s expression as inhibiting an intermediate step in the pigment pathway. Kyushu reports reduced activity in genes involved in melanogenesis where ARHGAP36 activity is high, while noting that the exact action is not yet known.
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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →The two teams reached the same broad conclusion independently, using complementary evidence: Stanford emphasized X-chromosome variant screening and melanocyte-specific expression, while Kyushu reported cat samples and expression comparisons in calico patches. Together, the studies identify the long-sought genetic basis of the sex-linked orange trait, while leaving details of the downstream mechanism open.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Does an orange coat predict personality or health?
No. The studies do not establish a distinctive orange-cat personality or a health condition caused by the orange variant. Stanford reported no expression differences in the kidney, heart, brain, and adrenal gland samples it measured, but those results do not address every tissue. Lead author Christopher Kaelin said, “There are not many scientific studies of the personality of orange cats.” Kyushu likewise describes proposed personality links as lacking scientific evidence.
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