The easiest way to sex a kitten is to compare the litter and the differences will then be obvious. However,even experienced breeders and vets have been known to get the sex of a kitten wrong, so that George eventually ends up Georgina.
For the male kitten, the bum looks like a colon, with the top dot the anus and the bottom dot the sheath for its penis. Also, sometimes the bulge of the testicles can be seen.
With female kittens, the bum looks like an upside down exclamation mark, with the top dot the anus and the vertical line the vagina.
Here is a photo of one of my male kitten’s bum. The kitten is lying on its side, the tail is on the right. The bulgy bits are just above the lower dot.
Here (photo below) is the female kitten’s bum. She’s lying on her side as well. Her tail is on the left. As you can see, it is altogether more discrete and neat-looking arrangement than the male’s bum.
Another method is to sex using colours. Red (ginger) is linked to the X chromosone. Chances are most kittens with some ginger in them tend to be boys. Most tortoiseshell cats are girls. However, if both sire and dam carry red, then there is a strong possibility that there are female ginger kittens.
And this has seemingly proved the case with this year’s litter of 5: the 2 boys are the classic tabbies, while the 3 girls are a red silver shaded and two red tabbies.