When going through the game as a man (specifically "voice is lower than yours, but people assume you are a man often enough" + "boy" from An) you can unlock the kindness option, but if you do the same options but choose "girl" instead of "boy", you cannot unlock the kindness option. Is this on purpose or an error? 

Something else might be different. That choice combination alone doesn’t affect kindness value. (let me know if you want to email me both save files for me to try to figure out what’s different)