DEAR HARRIETTE: This Christmas, I'll be meeting my boyfriend's family. They live out of state, and it's the first time we'll be face to face. We have been dating for nearly a year now and I really like him, so I'm looking forward to getting to know his family and see how he grew up. I want to make a great impression, but I'm a bit nervous. Do you have any advice or tips for making a positive impac…