Calico cats are usually female. That may seem odd, but it’s one of those facts of life that can’t be denied, unlike climate change and the popularity of Kim Kardashian. In case you’re wondering, there’s actually a scientific reason why calico cats are usually female and it all boils down to chromosomes.

Females have two X-chromosomes, meaning that they can only pass down an X-chromosome to their offspring. Males, on the other hand, have an X-chromosome and a Y-chromosome. This allows them to pass down either an X-chromosome or a Y-chromosome to their offspring, determining the genetic gender. A female receives an X-chromosome from both of her parents while a male receives an X-chromosome from his mother and a Y-chromosome from his father.

In cats, the X-chromosome determines most of the fur color (with the potential exception of white). A male offspring only receives an X-chromosome from his mother, so that alone determines his fur color.

The presence of two X-chromosomes determines the calico coloring. Although some males have a calico coloring, it’s extremely rare, like an honest politician. That’s why most calico cats are female.

To read more about the scientific reason behind calico cats, click here.