My brother and I accepted our mother's version of the affair that produced our sister with few questions, even though Lydia looks completely different from the rest of us. Mom is a long-legged Latina, but my brother and I take after our father. We're both tall blonds. Lydia is petite and cinnamon-coffee dark with tightly curled blue-black hair.
It's not exactly a stretch to say that the episode is structured in three parts to show Don's past with his first wife demonstrating why she remains stuck in an untenable child-like mode, his present with his second wife and why her unstable situation is untenable for him, and his hoped-for future at his past employer Sterling Coo.