Aged 20

Lads, according to dubious studies, your sexual peak is behind you already – and, ladies, yours won't happen for another decade. So we're off to a good start. This decade of your life is also the one during which you are most likely to be hacked, as apparently we twentysomethings are three times more likely than baby boomers to keep our passwords on Post-it notes.

Aged 21

Rest easy behind the wheel, as at 21 you are less likely to be involved in a car accident than you were before.

Aged 22

Your mental powers start to peak, according to scientists at the University of Virginia. You have got about five years to think of something brilliant.

Aged 23

The "terrible teens" begin to subside, and girls stop arguing with their mothers. This is after an average of 183 quarrels with mum, apparently. Although if you are counting, you are being petty and are almost definitely in the wrong.

Aged 24

Gents, your peak strength is just about to expire, so spend this year flexing.

Aged 25

Since adolescence lasts until the age of 24, you are now officially an adult. Congratulations.

Aged 26

It's quarter-life crisis time! Get ready to feel weighed down by debt, dwindling job prospects and a general sense of impending doom. Far superior to a midlife crisis, the quarter-life crisis doesn't involve a sports car purchase you can't afford and happens long before you start to look ridiculous at the gym.

Aged 27

This is where, if you are combining drug addiction with musical brilliance, you might well join what Kurt Cobain's bereaved mother referred to as "that stupid club". If you do live, this is where a decline in brain speed, reasoning and visual puzzle-solving ability begins.

Aged 28

Supposedly, women are at their happiest at 28, because all of life's most important things have fallen gloriously into place. Job security, a steady income and a stable relationship (very common among under 30s, as we all know) – and, most importantly, as the spokesman for the company that carried out the study pointed out, "their hair looks the best, body shape is at its peak". Apparently, 28 is the age you become those women from TV ads who laugh while eating salad.

Aged 29

Welcome to hangovers. No longer are they just an excuse to watch an omnibus on TV and eat whatever you damn well please; hangovers supposedly start to hit hard at the age of 29. What used to mean a slow start to a Saturday becomes something between a mild medical emergency and the strong suspicion that demons are trying to escape from inside your brain.