1. Genetics of Calico cats

2. Tortoiseshell—no white patches

3. Calico with white patches—white is controlled on a separate gene.

4. Calico cats: X linked gene
In cats, base coat color is on the X chromosomes.
Male cats have only one X chromosome, so can only express one base color.
Females have two X chromosomes, so can express two base colors. For example, say the sire of a kitty contributed the black gene and the dam contributed the orange gene.

5. The inactivated X chromosome is called a Barr Body.
Dosage compensation keeps females (XX) from expressing twice as much of X-chromosome genes as males (XY), who have only one X chromosome.
Both sexes are rendered roughly equal by the inactivation of one X chromosome in females.
The inactivated X chromosome is called a Barr Body.
Barr Body

6. Calico cats: X-inactivation in action
It is thought that early in embryonic development, X-inactivation occurs randomly (maternal or paternal chromosome is not targeted) in somatic (body) cells of females.
Once inactivation has occurred, the same X chromosome will be inactivated in future cells after mitotic cell division.

7. When some of the black alleles are inactivated, and some of the yellow/orange alleles are inactivated in other cells, the results are a calico cat

9. Does cat coat color determine personality?
A study published in 2012 researched how people perceive cat personalities based on coat colors.
Interested to know more? (can be used as a Current Events extra credit article…)
news.berkeley.edu/2012/10/23/cat-color/

10. Videos Why are calico cats female? Polydactyl calico
Polydactyl calico
Calico cat stalking hungry squirrel