Determining the sex of the kitten sometimes is a guessing game. Other times, it is pretty straight-forward. An easy rule of thumb: If you cannot identify the gender through the color (a sex-linked gene), if the genital area resembles a colon (:), it is a boy; if it resembles more of an upside-down exclamation mark (¡), then it's a girl. The openings on a girl are about half the distance apart as those on a boy.
At the end of Day 3, the kittens' weights are as follows:
Baby #1 - 4.7 oz.
Baby #2 - 5.2 oz.
Baby #3 - 4.6 oz.