Often I wonder why some people's facial expressions differ sometimes regardless that we all have the same set of muscles. I still don't know exactly why for example some people's lip corner turn upwards when smiling while others just go sideways, I'm guessing it has something to do with variations in muscle insertions around the perioral region. Which made me wonder whether mimetic muscles can be manipulated surgically someohow, surely doctors have dabbled with that at some point?