Im not sorry to disagree with you sphere. oompa doesnt know jack shyte for sure. He is going off second hand knowledge that he got from a man who is now dead.
I agree with you here, and under the circumstances that Oompa described, I think he should just butt out.
However if it were true, I believe an adult has that right to know about there parentage. The child should not have to pay for there parents indiscretion. I can see where everyone would like to just pretend it never happened, but it did, and part of the repercussions of those actions is that someday you need to fess up to the kid.
And as someone else mentioned, maybe the kid does know. but just doesn't advertise it. I'm hoping here that one of the parents stepped up and did the right thing when the kid was old enough.
But no, if I were Oompa's shoes, I would keep my mouth shut.
(hoping that someday someone tells me that I was switched at birth, and my parents aren't really my parents.