Is there some reason to think that physiognomy really works? Reverse causation is probably the main reason, e.g. tall people are more likely to be seen as leaders by others, so they are more likely to become leaders. Nevertheless, is there something beyond that?
The 2014 LW survey results mentioned something about being consistent with a finger-length/feminism connection. Maybe that counts?
Some diseases impact both reasoning and appearance. Gender impacts both appearance and behavior. You clearly get some information from appearance, but it's going to be noisy and less useful than what you'd get by just asking a few questions.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.