Duodecades are superior to decades, and we can take overlapping pairs of duodecades as "generations" to solve the dividing line problem.

Duodecades:

  * 1968-1980
  * 1980-1992
  * 1992-2004
  * 2004-2016
  * 2016-2028

Overlapping generations:

  * GenX: 1968-1992
  * Millennial: 1980-2004
  * GenZ: 1992-2016

Precise boundaries are clearly problematic but you can’t claim that someone born in the late 60s had the same type of global view that someone born in the late 80s did.

The BMI scale is useful. Yes, athletes and bodybuilders it may not be accurate for, but being on HN I think you are neither :)

Currently, I am at 20 BMI, for reference.