Again, for all I know, he could have presented himself differently during his term in office, but after his term was up, his life seems genuine to me.
He was the opposite of narcissistic, he was honest to a fault, telling the truth even when it was unflattering to his public image: he freely admitted - and without direct prompting - in a Playboy interview that he had looked at a lot of women (other than his wife) with lust[1].
1. WARNING - site is on a Playboy domain - you may not want to open this on a work computer or have any anti-NSFW mononitoring of your browser activity. https://www.playboy.com/read/playboy-interview-jimmy-carter/
Once I understood how it works, I can easily spot people including politicians using these quite simple manipulation techniques, and I feel quite stupid for not figuring it out on my own at a younger age.
This would be diametrically opposed to American culture lol