All it takes will be for a few states to require this.
This has the potential to get very interesting. I don’t know what he’s hiding, but he’s hiding something.
I figure that it's just something trivial, but politically-damaging.
'Twould be hard to run as "The First Black President" if your BC lists your race as "Caucasian", for example. Would need to be something that would cost him votes, en masse.
Just my opinion. YMMV.