Like calicos, most tortoiseshell cats are female, and males have an extra chromosome. When this condition occurs in humans, ...

Most tortoiseshell cats are female, like calicos, so if you have a male tortoiseshell, consider yourself extra lucky. A ...

Brynn, the Westfield Stray Cat Rescue Cat of the Week, is a striking adult female Tortoiseshell cat. Brynn has a super soft coat of fur and she loves to be petted. Brynn is shy at first but once she ...

A prime example of X inactivation is in the coat-color patterning of tortoiseshell or calico ... which explains why almost all calico cats are female. X inactivation exists in two different ...