This particular topic doesn’t have roots in the liberal or conservative sphere, but it’s “fake news” that is still spread throughout social media and conversation.
(Disclaimer: I’m left handed)
To begin, logically, there would be no correlation between handedness and length of life. I don’t know how else to explain this other than false correlation. How would such a minor thing affect one’s health? Perhaps left handed people have a twitch that makes them stab themselves in the eye. Come to think of it, I am twitching a bit..
Fun Fact: Left handed people make up only 10% of the human population.
Where did this rumor come from? Well, its roots come from (poorly studied) 1988 and 1990 scientific journals that attempted to correlate longevity with handedness.
If you’d like to read more, here’s a Snopes article about it in full detail: Do Left-Handed People Die Younger Than Right-Handed People?