I can tell a cat's gender just by looking at its face

you can sometimes tell a cats gender from the face because usually male cats have chubbier cheeks and a rounder face than female cats however it's more common in males that haven't been neutered as kittens since it's a testosterone thing. males usually have thicker skin and round cheeks/jowls to protect their face and neck when fighting other male cats. this doesn't go for all male cats though as some don't have the chubby cheeks.

you can also sometimes tell by color since female ginger cats are more uncommon than male ginger cats because to get a ginger female both her parents must have ginger on them (for example both cats have to be ginger or the father ginger and the mum tortoiseshell/calico) so when you see a ginger cat it's more often male than female.

tortoiseshell and calico's are also predominately female, a male can be tortoiseshell/calico however it's very rare and male tortoiseshell/calico's are infertile since it's only the cause of a mutation called klinefelter syndrome

I can tell without looking at it

So can I. Female cats are slimmer and even if its a fat cat they are slightly smaller in size to male ones. Females also do have slightly different facial structure.

I can tell OP's gender by their punctuation

I can tell a dog's gender by its face and body

A can tell by it's color