I don't know what area of goergia the OP's cousin is. But here just north of Atlanta, drug use and alcohol use is rampant among the teens. There has been numerous reports of parents buying their teens alcohol at their parties etc. it is really bad.
I have heard of homeschool kids smoking and the parents not being aware of it. Homeschooling or not does shelter kids from influences. Unfortunately, even vigilant attentive parents sometimes miss the clues so it is really hard. I just pray my kids don't fall prey to it. I can't chain them to myside 24/7.