Socially Acceptable

I’ve often wondered why sex with multiple people seems so taboo and “wrong”… Why are some forms of physical expression fine, and others aren’t? No one judges for a public hug with a fairly new acquaintance, or a peck on the cheek from a foreigner, or a kiss between boyfriend/girlfriend. I understand there’s a time and place for everything, and I wouldn’t want to see someone having sex in public (okay, maybe I would), but I really want to know how these social norms got started because when you begin to examine them, a lot of them just don’t make sense. Why can’t affection just be affection, and pleasure, pleasure? It’s okay for girls to touch each others’ hair but not their breasts… It’s okay to shake a stranger’s hand but not touch their ass… I just find it all very interesting, and frustrating. And this is coming from someone who insists on a wide radius of personal space. ;)