(Philly.com, Nov. 22) Marijuana use among youths between 12 to 17 is increasing, from 6.2 percent in 2002 to 8.4 percent in 2014. Who's partly to blame? Their parents, experts say. That's because the level of potency of today's marijuana is far higher than the previous generation's, but parents don't realize there's such a significant change. THC, the chemical in marijuana that creates the high, was about one percent in the 1970s - compared to 11 percent today. In terms of beer, that's like three percent alcohol jumping to 33 percent. And more THC in the body can cause more damage to teenage health and brain development. READ MORE.