It's a long way from the 1950s, when comics were blamed for juvenile delinquency and the subject of U.S. senate hearings calling for censorship. So rest assured that your child's love of superheroes is not just fun, but meaningful, and because you grew up with the same ones it's a great cultural meeting point for mom and dad, too.
I haven't seen any surveys that say definitively how many five to twelve year old girls are frequenting comic book stores and watching Star Trek. I'm sure that the number, whatever it is, is higher than the numbers were in the 1970s but I'm willing to bet that it still disproportionately less than the number of boys.
After walking the floor at Montreal Comic-Con for a few hours on Saturday, one thing became abundantly clear: the majority of the commercial activity that was taking place at this physical event cannot be duplicated or replicated in a digital format. By cultivating true fans and giving them unique opportunities to connect and share, they're not only keeping alive a traditional media channel (or two), but they're inventing new and fascinating ways to extend their characters and build interest.
Even as comic collecting declined in the 1990s, its fan-oriented subcultural set-up spread to other groups who began joining forces for broader genre cons like Fan Expo and Comic-Con, while slowly turning their favorite things, be it Lost or Lord of the Rings and the contemporary comic-book movie, into mainstream success stories.