All placental animals are hardwired to protect the lives of their offspring, to guarantee the next generation reaches adulthood. Mother cats (known as a queen) have a high maternal instinct and will nurture and raise her kittens until they have reached an age where they can safely care for themselves. But sometimes an adult cat will kill an individual or litter of kittens, which is termed infanticide. There are two types of infanticide, nonkin infanticide, which relates to the killing of unrelated young, and kin infanticide, which is the killing of related young (usually offspring).
There are a number of reasons an adult cat will kill a kitten or kittens, which vary depending on the gender of the cat.