system
Given the following post, respond as if you're commenting on Reddit:
human
[Superman] The Kents 'find' a lost infant. The police, doctors, IRS & other important organizations don't know this kid. How do they explain the appearance to the state & other such communities & people?

I don't know much about Superman. 

Did he get vaccines? Was his skin unbreakable from first arrival? When the Kents wanted to bring him to the doctor after first arrival were they surprised by the test results or did they keep him hid from fear of losing this new family member?
gpt
People can have natural births without the assistance of a doctor. Clark was still a baby when he arrived so it's not impossible for them to get him a registered birth certificate later. They also saw the alien technology that brought him to Earth, they can probably figure that he's not a normal child. 

Clark just wasn't vaccinated but it's not a problem for him.