Orange and white kittens are common because the gene that carries the orange coloring is dominant over all other colors. If a kitten receives the orange gene, it will have orange on its coat somewhere.
Orange male cats are more common than orange female cats. The orange gene is carried on the X chromosome, of which males have one. Female cats have two X chromosomes. The male cat only needs one orange gene to develop an orange-colored coat. The female needs two orange genes to achieve the orange coloring. Orange and white cats are classified as tabby cats. There are no solid orange cats.