body/facial hair on both genders is due genetics
there is misconception that if you have hair your hormones are high or vice versa.. that is not true. however if you increase hormones on both sexes the hair will grow faster and more.
i'm a very hairy person, many meditarrean are and it 100% has to do with evolution. body hair helps you in that kind of climate adjust to both summer (protecting the sun) and winter (warming you up).