I put it off longer than any of them. Aside from consistent lifting and diet for the first solid 8 weeks of my life, I don't know what else changed in the last 2 months.
Sometimes you're just fucked in the proverbial gene pool like that.
I started getting thin @ 21, and been shaving about 2yrs now. Once I did shave it, I thought "Why didn't I do this sooner?"
Sometimes stress is the biggest factor, and if that is indeed true, that's the reason why I lost mine! Uncle, Dad, everyone on both sides of my family has a full head of hair, except me. Gramps is thin, but has more hair at 80, than I did at 27. Oh well, that's life.
It's what you make it, and if you worry about not having hair, than the others around you will worry about you not having hair.