Yeah I totally understand that- even humans have trouble sometimes. I'm surprised you even tackled that since everything else seemed to be pretty good.
Just out of curiosity what are some things you expect people to use the gender selection for? I could imagine a toy app that puts hats on people and, if the gender confidence is high, assigns them a "female" or "male" style hat (and a more unisex style if the confidence is lower).
Gender estimation is a must-have feature in modern face detection / recognition software. However, I'm not sure where it is used in real-life besides targeted advertising or some toy applications as you mentioned. For now, we will leave it for our users to decide how to use this feature.
This is intended to be a drop-in replacement (sign in, create namespace, update the endpoint address to http://api.skybiometry.com/fc/ and use your old code) for face detection and recognition. Detection of some face attributes is still missing but we are working on it. And we use our computer vision algorithms, so expect slightly different results.