What happens if cats mate with close relatives?

Cat inbreeding can cause genetic defects and health problems because it raises the chance of hereditary disease and mutation, increasing the offspring’s disease risk. Common defects include vision, hearing, heart, bone, and immune-system issues.

For the kittens’ health, avoid inbreeding; when your cat reaches breeding age, have it spayed or neutered at a veterinary hospital, or keep males and females separated.