Look, all this talk about Kryptonite is bogus. This is not a real weakness. I mean all of us would die horrible deaths if exposed to any number of radioactive materials, spores, poisons etc, etc, etc... The fact that Kryptonite is not only rare on earth, but the only thing that can weaken and/or kill him is not really a legit weakness.
Supermans true weakness is..... Pride.
It's his own arrogance and pride that has led him to time and time again put the world and himself in peril. He always swoops down without a milisecond of forethought or reflection and just assumes that his incredible power will be able to fix the problem.
In many ways this completes his allegory of being the imbodiment of the USA.
Well, the basic idea behind it is that it is material from his home planet... and on his own planet, he *isn't* a superhero... he's just normal. So, being around material similar to himself can take away his special powers. Now, of course there is a lot more to it through different Superman storylines, but that is the closest I can get to "why." ...
Superman has two weaknesses. One of them is kryptonite. His other weakness is magic.
super kriponite aouto maticcly kills him
Superman, because Spiderman is human and has no Kryptonite. spidey isn't batman and therefore webs no worky on man of steel so no webs a fight of strenght between the two superman wins in 5 mins so long because of spideys spider senses
yes they do have a kid together. supermans son is superboy and he has no weakness to kryptonite because superman conceived with a human