Talk:Succubus/@comment-71.184.143.100-20150727204515/@comment-26097222-20150811071354

It originated, AFAIK, in basic avian biology. Birds that can fly have a keel bone and extra muscle across the chest. Human-like females lack both. The only place you could put functional wings without making gross (both senses of the word) alterations to anatomy is just above the hips.