The PG-13 movie rating is 20 years old. Back in 1984, “with no middle-ground between PG and R, the ratings board of the 1980s frequently wrestled with the right way to classify movies that should and should not be viewed by children. The flaw in the Motion Picture Association of America’s rating system was that it lumped all children — from infants to 17-year-olds — into the same group.” Then along came Steven Spielberg, who “invented the category. And “instead of being solely an extra warning to parents, as it was originally conceived, it has evolved into the preferred rating of studios and filmmakers. PG-13 puts “hot sauce” on a movie in the viewer’s mind.”