The news that David Obey, the longtime Democratic House member from Wisconsin, is going to retire from his seat rather than attempt to secure reelection against a surging Republican named Sean Duffy is fascinating in many ways, particularly how, in this year, Obey’s seniority and chairmanship of the Budget Committee are clearly liabilities with voters rather than positives. But culturally, there’s something more telling. Duffy is a county district attorney in Wisconsin. Before he became a lawyer, he first came to prominence as a member of the cast of “The Real World,” the pioneering MTV reality series. (His wife Rachel Campos is also a veteran of “The Real World,” though they were not on the show together; they met as part of a reunion show, and they have six children.) If Duffy wins, he will be the first person to emerge in politics from reality television. That may sound like something silly, but there was a time when people scoffed at actors getting involved in politics (“Imagine Broadway Melody of 1984,” sang Tom Lehrer when the second-rank hoofer George Murphy made it into the Senate as a California Republican in 1962). Indeed, people still scoff, which led a great many people to smile dismissively at the possibility of Al Franken winning the Minnesota Senate seat. And yet there Franken is. The Duffy example, if he’s successful, may even incline some young go-getters to do whatever they can to get onto a reality show to launch a political career. You heard it here first.