Another anecdotal experience: zero of my friends drink soda at all. We're all in the US in our late 20s. It's definitely a cultural thing, because we're all different kinds of people with different diets, different weights, etc. No one is diabetic.

On the other hand, 100% of us drink alcohol, and so far the only people I've met who are my age, from the US, and don't drink are recovering alcoholics and people whom I've later discovered are extremely anxious and worried about the possibility of feeling "out of control" (which is a totally valid reason not to drink).