Lusha lifted her reluctant cat Tiger up onto the exam table for the annual examination, parasite control and vaccinations. I figured without looking at the records that Tiger was a male because he was orange. Egg on my face again. I was playing the odds and lost. The gene for the orange color is located on the X chromosome.
Female cats have two X-chromosomes.
In fact that's what makes them female. In order for a female cat to be orange, she has to have the dominant gene for orange on both X-chromosomes. Later in the development of the fetus, by the time the skin cells are developing, only one X chromosome is needed in each cell. One or the other X chromosome in each cell is randomly chosen to be inactivated. When development is complete, the patches of skin cells that developed from cells with the orange gene active will have orange hair.