That's from http://www.kitten-rescue.com/kitten-res ... e%20kittenIn kittens younger than about two weeks, it is often difficult to tell their sex. Even competent rescuers and vets can be fooled! A female kitten will have what looks like an upside-down exclamation mark, whereas a male will look more like a colon. Also, the male's urinary opening is lower than the female's and he will also have a little lump between his anus and this opening. This will later become his testicles. Another way to tell is gently squeeze the urinary opening. If the tip of the penis appears, there's your answer!