"sin" does not mean "guilty"; it means "less-than-ness".
Adam had a choice, but prior to that choice, he was not affected by a "less-than-ness" of his physical nature. Once he made that choice however, everyone was affected by an inherited "less-than-ness" of their physical nature (as was the entire cosmos - Rom 8:20), except for one man, who inherited a different set of male genetic material, which was not tainted by this "less-than-ness".
This other man was the Second Adam, who also had a choice, unaffected by a "less-than-ness" of his physical nature. This Second Adam made the right choice, and as a result, those who follow him are free from the condemnation of this law of "less-than-ness" and its resulting death, and in the future, will experience life given to their mortal bodies by the same spirit that resurrected the Second Adam (Rom 8:1-11).
