The Kids Are Alright (2010)

When searching for a term to describe it, I settled on 'authentic.' The portrayal is a nuclear family filled with non-standard roles, save the kids who portray fairly typical teenagers.

The climax of the movie gave a glimpse of how the family could have grown to accommodate another member and grow in a different direction, yet the conclusion has the family remain true to itself. It was funny without using a single punchline. You really should see this movie.