Many times, the most difficult creative process is going to be the most personal one. This year, filmmaker Ben Stiller is offers up a documentary about life behind the scenes in his family. To be clear, this isn’t about what went into Zoolander, Dodgeball: A True Underdog Story and There’s Something About Mary. This goes back one full generation to focus on his famous parents. The duo of “Stiller & Meara” laid the groundwork for many comedians coming down the pike. But this profound, personal look at the Stiller family shows that it wasn’t always smiles and laughs bringing up two children all while headlining night clubs and other ventures…