In the Babylon-5 stories, most Minbari are bald, but some Minbari men have beards.
The Wikipedia article on Minbari says "due to the intermingling of human DNA into the Minbari gene-pool courtesy of Valen, some males are capable of growing facial hair."
Spoiler from episodes "War Without End":
Valen was a human named Jeffery Sinclair who went one thousand years back in time to lead the Minbari. He was transformed into a Minbari through a device called triluminary. He later fathered children on Minbar.
Is there a canon source that says "only male descendants of Valen may grow beards"? Or is that an unjustified claim posted on Wikipedia?
In accordance with my "Quotes Get Votes" policy, I prefer answers that have quotes from original sources. (e.g. - Interviews with J. Michael Straczynski, quotes from scripts, or video clips from episodes, etc...)