This, or similar, quotation has appeared in many guises and with many attributions.
“He who is not a républicain at twenty compels one to doubt the generosity of his heart; but he who, after thirty, persists, compels one to doubt the soundness of his mind.”
Anselme Polycarpe Batbie 1875
I was perhaps a decade or so late in coming to my realization, but better late than never.
I have decided to update my avatar. There were two thoughts behind this, both age related. I had been using anarchist memes and I realised I am too old to be using this modern visual shorthand for thought. It really didn’t sit well with my carnaptious elderly status. Further, I have always seen myself as more of a goat than a sheep. Both in the Biblical sense of one move to sit on the left side after selection, and also in the anarchist sense of not being one of the sheeple. But perhaps the most obvious reason was to find an icon that succinctly described me and none seemed better than an old goat.