Jews have beards. Not mustaches, beards. And not those dinky goatees or van dykes. Definitely not soul patches. Real, manly, bushy beards, beards in which you can hide coins, buttons, or insects. Perhaps even small rodents, a mouse or a hamster.
And although the Reflexive Property of Jewish Beards (if Jews have beards, then all beards are worn by Jews) does not hold (counterexample: ZZ Top), a single look at Karl Marx and his glorious facial hair leaves little doubt to what ethnic group the man belonged to. And one would be correct in that assessment of Jewdom, for Marx's father, Herschel Mordechai, came from a long line of rabbis. He was not allowed to practice law as a Jew, converted, and became Heinrich.
And of course, Marx's ideas that stirred up much of the world even (and especially) after his death, found a large percentage of their followers among Jews. So much so that Marxism is considered by some to be a Jewish conspiracy (but that theory makes even less sense than hiding hamsters in one's beard).
It just makes one wonder what turn history would have taken if Herschel followed family traditions and became a rabbi instead of a lawyer. Who knows, Karl could have followed suit. He definitely had the beard for it.