1. The mating behavior of a cat's son and its mother belongs to inbreeding. Kittens born will have genetic defects, and kittens born may have stunted limbs, blindness, paralysis and so on. And the chances of survival will be very low, and life can't take care of itself. In addition, cats with other blood relations cannot mate together.
2. If you want to breed, you should choose the same variety that is not related by blood to mate, so as to reduce the chance of gene mutation.