[TrackerFF]

I can tell you this - most of my peers from HS that went on to work in physically demanding (often outdoors) jobs look around 10 years older than the average, while the ones that got cushy / low-stress indoors jobs still could go for late 20s / early 30s (I'm in my mid 30s).

My bet is on environment, stress, and genetics.

But those that by far aged the most, were the girls that would spend their teens and probably entire 20s in the tanning bed. Probably guys, too, but we didn't really have many dudes that focused on that.