age male cat can breed

Question
I know that female kittens come into heat at around 6 months.  At what age are the male kittens ready to breed with the female kittens?  I want to breed a specific male and female from 2 different families but also want to prevent brother and sisters from interbreeding.

Answer
Susan,

When paired with a female in season, males can become sexually active as young as 5.5 months or, maybe, even younger.  If you do not want brother sister breedings, someone will have to be altered or they will have to be separated!

Best regards... Norm.