Now, researchers from Kyushu University, Japan, have found the X-linked mutation behind orange fur in house cats. This deletion mutation, a type of mutation where a section of DNA is missing, not only explains the peculiarity of ginger genetics, but also reveals an entirely new mechanism for promoting orange coloring in animals.

The findings are confirmed by a second independent study by researchers at Stanford University, U.S., with both papers publishing simultaneously in Current Biology.

"Identifying the gene has been a longtime dream, so it's a joy to have finally cracked it," says Professor Hiroyuki Sasaki, lead author of the study, self-proclaimed cat-lover, and geneticist at Kyushu University's Medical Institute of Bioregulation and the Institute for Advanced Study.

For over a century, scientists have suspected that the orange gene is located on the X chromosome. Male cats, with only one X chromosome, will have orange coats if they inherit the orange gene. Females, with two X chromosomes, need two copies of the gene to be fully orange, making them less common. If females inherit one orange and one black gene, they develop the patchy or mottled coats seen in calicos and tortoiseshells.