As it turns out, a gene known as Taqpep cloaks tabby cats in stripes when functioning correctly. However, if the gene has mutated, the same species of tabby cat will instead sport irregular blotches.
The blotchy trait is recessive, so striped tabby cats still may carry the mutated gene and pass it to their offspring, the same way brown-eyed humans may carry the blue-eyed trait. The blue eyes or blotchy coat can only be visible if Junior gets the mutated gene from both Mum and Daddums.
Geneticist Stephen O’Brien, now based in Russia but whose previous lab in Maryland helped discover the gene, noted that the Taqpep gene is present in at least thirty-one separate feline species, but it affects coat patterns among those animals differently.
For example, cheetahs are regularly spotted, but a cheetah with the recessive gene will develop ink-spill blobs with dark streaks down its spine—a visual difference radical enough to have made researchers once speculate that this variant was a completely separate species.
How the gene determines the exact coat pattern for each type of cat is unknown, but the researchers believe that it sets the design very early in skin development, before any hint of spot or stripe is visible to the naked eye.
Then as the skin develops, patches of a highly-localized follicle gene called Edn-3, which in high concentrations works at the root level to make hair grow dark, put Taqpep’s design plans into action.
While the chain of command between Taqpep and Edn-3 remains shrouded in mystery, their roles seem consistent enough across a number of species for researchers to continue unraveling the warp and weft of cat genetics.