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Tortoiseshell
A mottled blend of a black-series colour and red, seen almost only in females.
EMS code: fGroup: Tortie / Calico
The genetics
Tortoiseshell arises from X-chromosome inactivation: a female carrying both a black-series colour and red expresses each in patches. It is almost exclusively female.
Cats in this colour
Frequently asked questions
Why are almost all tortoiseshell cats female?+
The red gene sits on the X chromosome, so showing both red and a black-series colour together normally needs two X chromosomes — i.e. a female.
Related colours
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