Silly question: how do you recognize a male from a female kitten? I can see the interrogation in your eyes. Are they making fun of us? Not at all. At birth, the genitalia of the males and females kittens are very similar, to such an extent that you can sometimes hear experienced breeders say that they have to wait a little before saying what they have in their litters.
If you have male and females in the same litter, you just need a bit of attention. However, if you have only males or only females, here's a piece of advice. At birth, the kittens' genitalia are not very developed, and the vulva of the female can be mistaken with the small testicles of the male. Take your kitten in one hand, and lift its tail with the other. You can see two orifices, of which the closest to the tail is the anus. In the female kitten, the anus is almost joint to the naus. In the male kitten, there are separated from above half an inch.From the 6th week, the genitalia of both genders are well developed, and there's no doubt left, even for someone who's no expert.And as two small pictures are better than a long speech, here's the genitalia of the kittens in pictures.
Young female: the anus is almost joint to the vulva.
Young male: the two orifices are half an inch separate from the other. The testicles are not developed yet.