Calico Kitten Offspring, Color Genetics and the Male Calico Cat

Interesting Pets - The Genetics of the Calico Color
A little calico kitten is just about as cute as a baby animal can be. However, a calico cat is not actually a breed but rather a very specific color characteristic. A "true" calico is a tri-color cat, with its colors in distinct patches, not mixed as in a tortoiseshell cat. However, there is more to a calico cat than just a mix of colors.
For instance, have you ever seen a male calico cat? Few have, as a matter of fact, word has it that all calico cats are female. To better understand this mystery, lets have a brief, very basic, review of genetics.
a calico kitten cat picture at
Each mother cat's offspring will carry a pair of sex chromosomes, XX or XY, the result of which will make the kitten either a girl or a boy. The mother passes an X chromosome down to it's creation and the father passes either an X or a Y. If the offspring receives the Y, it's genetic composition will be XY and it will be a male.
However, color and other physical calico kitten characteristics are tied specifically to the X or Y gene depending on the specific circumstance. For a kitten to be born a calico it takes two X genes, one carrying an orange characteristic and one carrying the non-orange characteristic (usually black). And, if a cat has the XX combination of genes it needs to be calico, then it would be a female, hence, why there is the perception that a calico cat has to be a female.
However, as life would have it, you will, on very rare occasion, run into a male calico cat. "But, how can this be?", you ask. Well actually, it is possible, rare, but possible just the same, that a genetic anomaly can occur where an offspring ends up with an extra sex chromosome producing the combination XXY. The XX of the XXY meets the requirement of the two X chromosomes needed to produce the calico cat characteristic's color and the Y of the XXY produces the male sex. However, male calico cats are usually sterile and do not reproduce.
So next time you see that cute little calico kitten, remember there's more to that girl than "meet's the eye".
By Lisa ... Journal Entry Posted 2-3-05

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