No matter how you slice the demographics, young people hold a lot of sway on social media. They influence social conversation, establish trends, and tend to help social sites thrive when they show up in large numbers. Part of this is the power of numbers. According to Pew Research, 82 percent of US adults age 18-29 actively use Facebook, though the 65+ demographic is no slouch at 48 percent. However a recent study highlighted by MediaPost suggests that one in three young social media users qualify as influencers.