mundane and pointless musing

Okay while driving home from work I was thinking about all the adopted people in the world. I wondered if there are indeed folks in this day and age who go through life never knowing that someone opened up their heart and home to let the adoptee into their lives.
Now if that should happen, what if that adoptee happens to meet the person of their dreams and decides to marry them for a happily ever after and their significant other ends up being their long lost sibling.
Does the state have to tell them that one of them is an adoptee? Does the state have to reveal they share the same parentage? Would the state knowingly allow a brother and a sister to get married even though the two are ignorant of their situation? What would you do if you were in this situation where you had already, to put it delicately, put the stones to your significant other but suddenly receive proof that person is your long lost sibling. Is it GROSS time or just keep quiet and don’t tell a gosh darn soul?
Please help because this is going to keep me up all night.

I believe this has occured. I think the couple was allowed to stay married.