Chat determining sex
It's a bit tricky to tell male from female when kittens are young.
It's very easy to tell when they're born, but they quickly grow more fur and it gets trickier.
If any of the kittens are calico (have both orange and black coloring; with or without any white), you can safely assume they are female.
Calico requires two X chromosomes, so it's extremely rare for a male to be calico and when it does happen they're usually sterile (and often have other problems).
That's the surest way to know, since vets are very experienced with kitten gender identification.
At 12 weeks old it's a small, but reasonably obvious, bulge.
At 8 months old (nearly fully adult) it's blatantly obvious.
If a kitten is orange it's somewhat more likely to be a male; for a female cat to be orange (or orange and white), its father must be orange.
This isn't as reliable unless you're totally certain who the father is.
Between 1 day and 10-12 weeks old it's tricky) I believe it's possible for a litter to be all females, but it's pretty unlikely.When they get their first vet visit, the vet will typically identify the gender as part of the routine examination.