Last line of your post is problematic. How does Shiv KNOW for HIMSELF what was there in hospital records? He only saw a torned page! The rest of the stuff is agreeable about his thought process.
@Tinoo
I am not scientific. Rather I'd be emotional! I'd be in denial even if my parents themselves told me. First reaction is denial. Who readily believes parents aren't his own?
Though I admit when I was little and I'd get angry or my parents would be angry with me then I'd feel if I was their own kid or not. Often if I'd feel parents and family are on one side and I am isolated then also I'd feel that way. Sometimes we compare features also.
Feeling or suspecting is something else. But believing it for sure as a fact is different IMO.