AN OVERWHELMING MAJORITY OF SCIENTIFIC STUDIES PROVE DEFINITIVELY THAT RIGHT WING BELIEFS ARE HEAVILY CORRELATED WITH LOW INTELLIGENCE:
Bright Minds and Dark Attitudes: Lower Cognitive Ability Predicts Greater Prejudice Through Right-Wing Ideology and Low Intergroup Contact
Low IQ & Conservative Beliefs Linked to Prejudice
Study links low intelligence with right-wing beliefs
Right-wing ideology and numeracy: A perception of greater ability, but poorer performance
Conservatism and cognitive ability
Intelligent people are more likely to be left-wing, says science
People with lower emotional intelligence are more likely to hold right-wing views, study finds
(Taken from pinned comment here)
The dihydrogen monoxide one was traditionally, in my experience, a conservative joke to make fun of the do gooders that wanted to not have toxic chemicals in the air, water, food, etc.
Going way way back to the 90s and before.