As the saying goes, "If you're not a liberal when you're 2.5, you have no heart, and if you're not a conservative by the time you're 4.5, you have no brain"
I think this one is popular in various forms, Goodreads ascribes it to G.B. Shaw: https://www.goodreads.com/quotes/11546984-if-at-age-20-you-a... - but I believe it's fake, also it's not on his wikiquotes page. "If at age 20 you are not a Communist" gives many results but it's really hard to track back the source.
consumer451|4 months ago
benterix|4 months ago
But after a bit of digging I got to this: https://quoteinvestigator.com/2014/02/24/heart-head/
Conclusion: many forms, many misattributions, many transformations by various authors, but the saying is definitely not made up.