I have noticed that a large number of male Jedi have facial hair if they are a Jedi Master or higher. Is there a reason for why a lot of Jedi have beards if they are Jedi Masters or higher?
For those that want some examples:
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Using the Star Wars wikia as a reference (I know, shoot me) we have the following "notable" Jedi Masters.
That tallies to 32 without beards, 9 beards and 3 unknowns. I think it's safe to say your assumption that most/a lot have beards is incorrect.
Restricting this to males only still puts this at 21 no beards, 9 beards and 3 unknowns which still challenges your assumption.