Pheromones make for a good story: a mysterious, invisible quality is what makes you "biologically" attractive (or not) to others - and you has no control over it. It's an easy out for the romantically spurned. A pheromone is simply a chemical signal transmitted between individuals of the same species, often eliciting a social response. Watch seven classic scenes with some very well know classic porn stars as they show you how sexual they are by "The Scent of a Female".