I accept it as a unfortunate fact that a certain percentage of people sent to prison are innocent. That has been and will always be true.
On the other hand, when such an instance is found out, heads should roll. (Discourages the habit.)
I would expect that in the overwhelming number of cases, there's someone in prison for something any one of us might have felt justified doing, had our lives been different.
Still, I am not so quick to blindly believe that this genetic testing is foolproof, no more than I have been to believe that all in prison are guilty.