Members of Gen X, the 65 million people sandwiched between the much larger groups of baby boomers and millennials, are often thought to be cynics, slackers and loners, a characterization brought to life in the disillusionment movie “Reality Bites.” In the first of six episodes, Generation X explores the roots of this generation by looking at the forces that shaped it, from the stalemate of the Vietnam War, the increasing divorce rate, the growing latchkey kid phenomenon, the resignation of Nixon and the rise of grunge.