Cat Genetics Part Two: Understanding Inheritance Basics
This article is part of a detailed series on cat genetics. If you have not yet read part one, we recommend starting there to understand DNA and genes before continuing.
How does inheritance work in cats?
Every kitten inherits half of its genetic makeup from its mother and half from its father, but due to chromosomal swapping during reproduction, each individual cat has a unique genetic profile. This genetic reshuffling means that even though the DNA comes exclusively from the parents, the combination is entirely new and varies significantly.
Gene pools and the impact of inbreeding
Maintaining a large gene pool is vital for the health of cat breeds. It's not enough for a breed to have many individuals; what truly matters is the diversity of genetic material. Many cat breeds started from a mutation in a single individual, such as the American Curl, which began with one cat exhibiting curled ears. Responsible breeders introduced outcrosses from domestic or similar breeds to expand the gene pool and reduce health issues.
In contrast, some established breeds like the Ragdoll in the UK began from few founder cats, leading to a limited gene pool and potential inbreeding issues. Similarly, the Burmese breed demonstrates how a restricted gene pool can exist despite a large population, underscoring the importance of careful pedigree research by buyers and breeders alike.
Is inbreeding always bad?
Not necessarily. Inbreeding occurs naturally in cats, especially in uncontrolled local populations where dominant males often mate with related females. This can lead to close relatives breeding, which increases the chance of recessive traits emerging. While inbreeding can concentrate desirable traits, it can also raise the risk of health problems.
Responsible breeders strive to balance these risks by understanding the genetics involved to maintain breed health and minimise negative traits.
Understanding dominant and recessive genes
Most genes come in pairs, one from each parent, but their interactions determine how traits appear. Dominant genes express their trait even if only one copy is present. For example, Polycystic Kidney Disease (PKD) in Persian cats is caused by a dominant gene—only one copy from one parent is needed to cause the condition.
Recessive genes require two copies (one from each parent) to express a trait, such as the cream coat colour. Carriers with only one copy usually show no visible signs but can pass the gene to offspring.
This genetic complexity means breeders must understand whether traits or conditions are dominant or recessive to make ethical and effective breeding choices.
Polygenic traits and genetic complexity
Genetics is often more complicated than single-gene inheritance. Many traits, such as coat colour richness or eye colour shade, are controlled by multiple genes called polygenes. This complexity can explain why some red cats have vivid colour and others appear paler, or why eye colour varies widely even within the same breed.
Responsible breeding and buying
Before buying a pedigree cat or breeding, it is essential to research pedigrees thoroughly. Understanding the genetic history helps avoid health issues related to inbreeding and informs decisions aimed at improving breed health.
Breeding cats responsibly is a commitment that requires knowledge of genetics and a focus on the welfare of the cats involved.
Additional Resources in the Cat Genetics Series
Explore more topics in our ongoing series:
