One slightly off-topic comment I have, however, is:
When the author talks about delayed adulthood and mentions that the percentage of 12th graders that tried alcohol declined, how is that possibly a trait of adulthood?
If anything, I'd say that not consuming alcohol demonstrates a more conscious choice that could be associated with adulthood. Also, one must consider the impact of hangovers only increases, thus increasing the correlation (I guess) between adulthood and the avoidance of alcohol.
"Tried" is probably the keyword here. Everything you said is correct, but having alcohol is something that adults, not children, typically do. Whether or not more mature adults move to alcohol avoidance is a different thing.
I think it definitely indicates a change in socialisation at the very least, and while labelling it an adult trait may be incorrect depending on who you ask, it is still relevant.
One slightly off-topic comment I have, however, is:
When the author talks about delayed adulthood and mentions that the percentage of 12th graders that tried alcohol declined, how is that possibly a trait of adulthood?
If anything, I'd say that not consuming alcohol demonstrates a more conscious choice that could be associated with adulthood. Also, one must consider the impact of hangovers only increases, thus increasing the correlation (I guess) between adulthood and the avoidance of alcohol.