Why do cats eat their own kittens?
I. Human odor interference
After a mother cat gives birth, some people may pick up the kittens out of curiosity or worry. When there are many people around, the kittens will pick up human scents. The mother cat may perceive the kittens as a threat by the scent and move them away. When she feels extremely frightened, she may take an extreme measure—eating the kittens to protect herself.
Second, kittens are not competitive.
When a mother cat discovers that her kittens are deformed, she is very likely to eat them. This is a result of natural selection; only the fittest survive. Deformed kittens are unlikely to survive in the wild, so they are eaten by their mothers. Another situation is that kittens die at birth or shortly after. Usually, the mother cat will move them to another location, but some mother cats may eat them directly. This situation is less common in domestic cats due to greater human intervention.
3. Insufficient maternal instinct in the female cat
Or perhaps the mother cat lacks maternal instincts, causing her to be unable to care for her kittens as her own children, both subconsciously and through outward behavior. There are many reasons why a mother cat might lack maternal instincts. If it's a genetic issue, the best solution is spaying/neutering; otherwise, you're very likely to witness a tragedy repeat itself. 
IV. Insufficient food
This mainly happens to feral cats. For example, at this time of year, mother cats themselves have difficulty finding enough food, so they have no choice but to kill their kittens to conserve energy.
5. Pica
Cats may develop pica if they lack certain proteins or minerals in their daily lives, are constantly under stress, or do not drink enough water. Some cats eat their own kittens during their first litter and may develop a persistent pica habit afterward.
VI. Other
One theory suggests that the mother cat's excessive pampering of her kittens or the stress of giving birth for the first time caused her to lose control of her care, resulting in the kittens' deaths. To prevent predators from detecting the scent of the dead kittens, the mother cat had no choice but to eat them.
If a cat is touched by a human and picks up other scents, the mother cat will eat her kittens as a form of self-preservation. This is a primal instinct for self-preservation in felines. The reason she eats them rather than kills them is because the mother cat, after giving birth, urgently needs to replenish her nutrients, is weak, and her hunting ability is slightly diminished; she simply eats the kittens. The cruelty of nature in its struggle for survival is beyond your imagination.
The idea that people born in the Year of the Tiger shouldn't look at cats is purely a myth. Most people who have seen cats have actually interacted with them and gained popularity from them. That's how the rumor got out.
Another reason is that if there's a weaker kitten in a litter, the mother cat, knowing she can't keep it alive due to insufficient milk, will eat it to replenish her energy and feed the stronger kittens. It's a matter of survival of the fittest.
Further Information:
Due to hormonal changes or external stimuli, mother cats are prone to developing mental illnesses such as depression. Therefore, it's crucial to pay close attention to their mental health and carefully observe their behavior. Newly minted kittens may refuse to nurse because their maternal instincts are weaker, and they may show impatience towards approaching kittens. In this case, the owner can gently press on the mother cat's body to help the kittens nurse, while simultaneously comforting the mother cat. Reward her frequently, and gradually reduce the pressure as she becomes more accustomed to the environment. Postpartum mother cats are also easily startled, especially when someone approaches or tries to hold the kittens. They may exhibit strong emotional fluctuations, which is actually a protective instinct. Therefore, people should minimize disturbance and prevent strangers from approaching the cat's nest to avoid agitating the mother cat.
