In particular, many people are represented multiple times, so I looked through the collection and tried to choose one good quality, representative, front-facing image per person
Appendix to “Is that a boy or a girl?”
Kerry Rodden

This is a good approach. In my own case I was influenced by another woman of transition who suggested the profile was the real gender test and where I borrowed “dead lock” as a phrase. It’s an ancient website but still up,

She writes of one of her photos,

this was actually quite a flattering angle; what you don’t see here is my profile, which always used to give me away.

There is an optical illusion having to do with brow bossing that really comes into play in profile. A European female nose appears to fold into the face below the eyes, while the optical illusion for a man is that the nose enters above the eyes.

Those in their 20s and 30s who transition can get away without bossing. As one person put it, they have that foxy look. I quipped that as we got older it turned vulpine.

Again, as a person of transition, my own concerns focus on profile and voice and I agree 100% with you when you say mannerisms and a thousand details we amass in a lifetime.