Is It Sexism or Racism?

Calico cat.Can you judge a cat by the color of its coat? Well, you can judge the gender by the color of its coat! Only 1 in 27 orange cats are girls, and more surprisingly, only 1 in 3000 calico cats are males!

Like humans, female cats have two X chromosomes and male cats have one X and one Y chromosome. The color of a cat's coat is determined by genes in the X chromosome. The X chromosome carries the black fur gene or the orange fur gene, not both. For a female cat to have calico markings, one of the X chromosomes needs to have the black fur gene, and the other needs to have the orange fur gene. Since male cats have only one X chromosome, it is not possible for them to be orange and black, at least not usually.

Sometimes, an egg cell will have two X chromosomes instead of one, or a sperm cell will have one X and one Y chromosome when it should only have one or the other. The cat will end up with the combination XXY, an extra chromosome! This also happens in humans and is called 'Klinefelter's Syndrome'. In cats, one X chromosome can have the black fur gene, and the other the orange fur gene. The result is a calico male cat that is usually sterile. The next time you see a calico or an orange tabby, you probably can judge whether it's a boy or a girl, and it isn't sexism or racism, it's genetics! Make a bet with someone!

About the Author

Willa Larsen, MS

Willa LarsenWilla Larsen writes on a wide array of topics for ScienceIQ. Willa received a BS in physics from University of Colorado and a MS in materials science and engineering from UCLA. She previously worked making infrared detectors for the Hubble, missiles and surveillance equipment. Willia is the publisher of which helps fund animal rescue.