Teenagers really are over Facebook. In February the social network warned investors that "our younger users ... are aware of and actively engaging with other products and services similar to, or as a substitute for, Facebook." And in April the investment bank Piper Jaffray reported that products and services like Tumblr and Twitter were further eroding Facebook's dominance among the Justin Bieber set. But why? In a deep report published on Tuesday, Pew Research explains that teenagers departing the social network's blue confines are looking for something more... real. More authentic.