Depending on your definition of "stranger", most Americans have been "perverts" at one time or another. Where is the "perversion" in having otherwise ordinary heterosexual sex with a person you haven't known that long? How about if you have sex with friends that you've known for years? This fixation with sexual behavior can't possibly be healthy. If "non-pervert" means "no sex until marriage and even then just the missionary position", then the "non-perverts" would be few indeed.