According to one of my books, KITTENS FOR DUMMIES, kittens have no interest in catnip until they are older. My 4 month old kitten has no interest in catnip at this time but was wondering what other people's experience was with this.
Did your book also mention that if the kitten hasn't inherited the appropriate genes to be a catnip responder, it won't matter how old they get, they won't like/respond to it?
A kitten with the appropriate genes to be a catnip responder also has to be at the age of sexual maturity - this varies a fair bit! I've seen in my breed, kittens as young as 4-5 months begin showing sexual maturity, domestic cats with siamese behind them (as I recall) may mature at a younger age.
I'd say if your kitten isn't responding to catnip by the age of 7-8 months, they aren't going to.
In which case, you can try the two alternatives to catnip, which some non-catnip responders will respond to - honeysuckle or valerian.
Oout of my 5 cats only one likes catnip. I tried to give it to Princess when she was a couple months old and she avoided the toy. She is now 11 and she still hates catnip.