Laura Dern and Sterling K. Brown both play supporting roles in complex family dramas this year with “Marriage Story” and “Waves,” respectively. Both parents themselves, they talked about the double standards that mothers, fathers and single parents can face while raising children. Dern also said she knew she wanted to be an actor when she was 7 years old, but her mother, actor Diane Ladd, discouraged her from entering the film industry at such a young age. Brown, who voices new character Lieutenant Mattias in “Frozen II,” also touched on how important it was to have a person of color in the mythical land of Arendelle.