In yesterday's NYT  Porchista Khakpour presents a little riff on the 80's TV show thirtysomething. It's a nice piece, reflecting on her childhood with immigrant parents, the cultural rootlessness of Gen-Xers, and her new found sense of adulthood upon reaching her thirties.  This graf struck me:

But now, as a writer playing Writer more than ever and a woman on the
verge of playing House for real, I find myself torn between the
decadent counterculture of my 20s and a desire for things “properly”
adult. And this is the very no-man’s-land paralysis that
“Thirtysomething” was obsessed with, that cold-sweat-panic moment when
youthful rebellion runs headlong into the responsibilities, pains and
joys of full-blown adulthood.

Maybe there's something about turning thirty (something that happened to me many, many years ago) that focuses the mind, that forces us let go of childhood pursuits.  Back in the sixties it used to be said: "Don't trust anyone over thirty" (did Jerry Rubin coin it?)  And that sentiment very much reflected the sense that thirty roughly represented the end of youthful insouciance.

This is not merely an American popular cultural thing, however.  Remember Analects 2.4:

For Confucius, adulthood is all about moral learning and achievement.  We have to cultivate our inner ethical sensibilities, teach ourselves and learn from others how to do the right thing.  It is a conscious, constant effort.  It begins when we are young, fifteen, and start to turn our minds to it.  But we do not reach the first stage of adult moral maturity until we are thirty – it is then that we can "stand firm."  Of course, moral development does not end there; it is a lifelong pursuit and performance.  But notice how thirty looms large here.

Clearly, a Confucian would invert the old sixties saw and say: don't trust anyone under thirty.  And he or she might even have some sympathy for thirtysomething.