Face features: can you guess the common link between all of the faces below?

 

Study the 32 faces above.  They all have something in common.  Based on nothing but their faces and expressions, can you guess what that common thread is? Are they...

• MENSA members?
• Democrat voters?
• Conservatives? 
• Antifa rock-throwers? (wait...Democrat pols assured us Antifa doesn't exist!)
• TPUSA members?
• the city council of San Francisco?
• PhD students in Sociology at Columbia?
• members of "By Any Means Necessary"?  (yes, that's an actual Democrat organization)
• trannies? 
• meth addicts?
• members of "Keep all drugs legal in Oregon!"

Okay, seven of those guesses are extremely likely.  And l let me quickly add that not everyone in the montage above looks crazy: at least two look relatively sane.