Calico cats typically have what genetic characteristic?

Calico cats are known for their distinctive coat pattern, which is a result of genetic factors related to their X chromosomes. Specifically, female calico cats typically have two X chromosomes, and each of these X chromosomes can carry different color alleles. One X chromosome may carry the allele for the black color, while the other may carry the allele for orange (or yellow). This genetic makeup results in the characteristic patchwork of colors in their fur.

The presence of two X chromosomes in females allows for such a combination, leading to the diversified coat color that is a hallmark of calico cats. In contrast, male cats generally have one X chromosome and one Y chromosome; as a result, they are usually not calico unless they have an unusual genetic condition (such as Klinefelter syndrome, resulting in an extra X chromosome).

This understanding highlights why the correct answer centers on the two X chromosomes with their respective color alleles, explaining the calico phenotype.