Girl cats get one X chromosome from momcat and one from dadcat. In the
case of calico and tortie cats, one of those chromosomes carries the black
gene and one carries the orange gene.

From http://www.petplace.com/cats/why-are-calico-cats-female/page1.aspx:

The story is different for male cats. Males have only one X chromosome,
and it is never inactivated. Whatever color gene is present on this X
chromosome will determine the color of the cat. Males can be calico or
tortoiseshell only if they are born with 2 X-chromosomes and a Y (XXY),
allowing one X to be inactivated. This genetic defect (XXY) is very rare.

Also:

It is difficult to breed specifically for calico or tortoiseshell cats.
Breeding an orange cat to a black cat may increase the chances, but it all
depends on whether the kitten is female and at what stage during
development the X-chromosome becomes inactive. There is no way to predict
or force an X chromosome to inactivate at a certain point in development.

Its just the way Calico's develop.  Its very nearly a sex linked
characteristic.  Almost to the degree that all female cats are female.  To
be calico a cat has to have two X chromosomes.  Girls are XX and boys are
XY.  In very rare circumstances you will have a male that is XXY.  But even
then it would be unlikely to end up a calico unless there were strong
determining factors on the female line.

Jo