The best storylines exploit the gap between perception and reality . The family that presents a pristine facade of "The Smiths" to the neighbors is usually the one hiding addiction, infidelity, or bankruptcy behind closed doors. Drama happens when the glass shatters.
Instead of two people talking through a problem, they use a third family member as a messenger or a buffer, creating a "telephone" effect of misunderstanding. Shared Trauma, Different Memories: incestiitaliani22nondirloapapa2011 work
A DNA test or old letter reveals a long-held secret (e.g., a secret sibling or a crime). The best storylines exploit the gap between perception