system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Why is Superman specifically weak against kryptonite?

From what I understand they are radioactive pieces of his homeworld, but what makes Krypton so special? Surely more worlds have exploded the way Krypton did and yet Superman isn't weak to their remnants, so what exactly sets Krypton apart?
gpt
I think the idea is that kryptonian radioactive elements harm kryptonians in the same way that earth-based radioactive elements harm humans. Due to his natural biology he has no defense of warding off it’s effects.