A 6-month-old kitten is not considered an adult. Generally, a cat's adult age is defined as one year, while a 6-month-old kitten is still considered a kitten. Although some 6-month-old kittens may already be in heat, this does not mean they are adults. Physically, a 6-month-old kitten may not yet be fully mature, especially in terms of bones and muscles.

Therefore, kittens over 6 months old still need proper nutrition and care to ensure their healthy growth. At the same time, it's important to avoid breeding them too early, as this can have adverse effects on their health. If you have any questions about kitten growth and care, it's recommended to consult a veterinarian or a professional pet care provider.