This is post #24 in the blogging A to Z Challenge.
My kitty Harmony has a beautiful dilute tortoiseshell coat. After adopting her in 2012, I learned that over 99% of tortoiseshell and calico cats are female. A cat’s coat color is determined in a large part by the sex chromosomes. Two X chromosomes are among the requirements to be a tri-color cat. This video does a great job of explaining. Enjoy!