Fact is there are quite a few gender clues we all use, most of them subconscious, and very hard to work through - it takes time, practice and the rest. The other ones, we add up. Which is why T helps guys to the point where it gives them facial hair, which is often enough to give one points in that direction. But given facial clues - and as humans we clue to the eyes from birth - for a lot of things, that added to skin, to size, to muscle mass and tone are often huge tells. After that, how you hold things, and yourself, and often very minor deals, are dead giveaways.
