Second, if we look at the wikibio of Kaye, we notice he:
-ran away to Florida as a young boy (Kramer allegedly ran away from home at age 17 and stowed away aboard a steamer bound for Sweden)
-had a strong interest in cooking, installing contraptions in his kitchen and making his own sausages
-was passionate about medicine (could have tried to be a doctor if his parents afforded it) and used to watch surgery on several occasions
-loved baseball(not much of a connection, as a lot of people love it)
-had a character he interpreted only at home, Kaplan, the owner of a rubber company (like the rich Van Nostrand and other Kramer alter egos)
-"Superman creators, Jerry Siegel and Joe Shuster, also fashioned a short lived superhero title, Funnyman, taking inspiration from Kaye's public persona" - this would point to Jerry's obsession with Superman and various similarities with that
show
- their overall body language, excluding the effeminate gestures of DK
