Amos, the original thinking regarding the first completed map of the human genome was that 95% of the genes were junk DNA. Now we feel that most of the junk is for the most complex protein formations.
The other unidentifiable DNA is for traits that are unexpressed in our current enviorment but when stressed, such as by an extremly cold climate, the gene that layed dormant would engage and produce hemoglobin that would transport Oxygen even in near zero temperatures. Of course that is a hypothetical example but the point is that we may have abilities that we may not even be able to imagine until they are needed by our children