I think (with nothing to go on but the few Kryptonians I've heard of) that you pass down the part of your name after the - to your kids, but it passes down differently depending on if the kid is male or female. Like, theres' Jor-EL, then Kal-EL, then Kon-EL (Conner's actual name). And then Kal-el's mom's name is La-ra (Er, I don't actually think most people write that with a dash, maybe? But it works with my theory), which the -ra was from her mom, because then we have Ka-ra, who is Kal-el's maternal cousin, I believe. So, like Sol-van's *sons* would be something-van, and his wife's name was something-ra, so we get La-ra from that. So if Kal-el had a sister her name would be something-ra, etc. etc.