No one thinks social media is kid stuff anymore, right? If they do, they should check out this CNET article that says more than 72% of US adults now use social network sites, that figure up from 67% just five months before, CNET reports, citing just-released Pew Internet Project figures. And that’s not just young adults. “One of the more striking stories about the social networking population,” Pew says, “has been the growth among older internet users in recent years. Those ages 65 and older have roughly tripled their presence on social networking sites in the last four years – from 13% in the spring of 2009 to 43% now.” Grandparents probably figure in there pretty prominently, which is great for everybody. Two-thirds (67%) of US adults use Facebook. As for Twitter use, Pew found that, now at 18% of US adults, it has more than doubled since November 2010. Here, the growth is more at the younger end of the spectrum: 30% of 18-to-29-year-olds use Twitter now.