I don't think it's so much a matter of wearing a beard, but being allowed to wear one.  For seven grim decades no American man could get away with a beard, after the end of the post-Civil War era, in which a beard was the sign of a veteran (try shaving in the field!)  Mustaches (often handlebars or toothbrushes until WWII) were the limit of tolerable facial hair among respectable company employees.

That began to change in the 1960s, when many things did.  Still, hippies and musicians and poets wore beards but few others did; facial hair didn't really take off among the gen. pop. until the 70s.  

But somehow, programmer beards were tolerated, first at universities, then at research labs, and then throughout the industry, then throughout every industry, though I myself was one of only two beards at the Wall Street brokerage I worked for in the early 80s, the other being my boss.  Even today, $EMPLOYER, which is an ex-startup, has a mixture of beards and no-beards among the male engineers, but all the sales and marketing males are clean-shaven.

(When I met my future wife I was 21, and she wanted me to grow a beard, so I did.  Since then I have occasionally asked cow orkers who have complained about shaving why *they* don't grow beards: the most common answer is "My wife doesn't want me to."  *My* wife doesn't believe this story.)

John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org
And through this revolting graveyard of the universe the muffled,
maddening beating of drums, and thin, monotonous whine of blasphemous
flutes from inconceivable, unlighted chambers beyond Time; the
detestable pounding and piping whereunto dance slowly, awkwardly, and
absurdly the gigantic tenebrous ultimate gods --the blind, voiceless,
mindless gargoyles whose soul is Nyarlathotep. (Lovecraft)