As thekraut said, the ginger gene is carried on the X chromosome, but is recessive. Because the mutant gene is carried on the sex chromosome, it is knowm as 'sex-linked recessive'. A male carries only one X chomosome, so if that carries the ginger gene is makes the animal visually ginger. There are ginger females but in order for them to show the ginger they have to carry it on both X chromosomes - the sire would have to be ginger and the dam to at least be a ginger carrier(come from a ginger father).