Here's why:
* Kittens are not sexually mature: Female cats typically reach sexual maturity between 4-6 months of age. A 1-year-old kitten is likely already sexually mature, but a male cat still needs to reach a certain age and size to be able to impregnate a female.
* Physical development: Male cats need to develop physically before they are able to produce viable sperm. While they may show interest in mating, they are not yet capable of impregnating a female.
Important Note: If you have a male cat and an unspayed female cat, it's crucial to keep them separate to prevent unwanted pregnancies. Spaying and neutering are the most effective ways to prevent unwanted litters and health issues.