It takes a complex and confusing combination of genetic markers to create a dilute calico cat. The short explanation is that a dilute calico must inherit three specific genes: a mosaic gene that allows two basic colors to be expressed instead of only one; the dilute markers of the two basic colors; and a white spotting gene that causes parts of the coat to be white. Only when all of these markers are present can a cat be a dilute calico. Because basic or dense colors are dominant, most calico cats' coloring is dense instead of dilute, even if they carry dilute genes. It takes the expression of the recessive dilute genes to create a dilute calico.