If your characters say exactly what they mean, you don’t have a drama. You have a deposition.

A past trauma or hidden truth (an affair, a financial crime, a "lost" sibling) that acts as a ticking time bomb. The Inheritance War:

Every family operates on a set of invisible rules. Who is the caretaker? Who is the failure? Who is the peacekeeper? A great storyline begins when someone breaks that contract .

Compelling family dramas often center on specific "cracks" in the unit that force long-buried emotions to the surface: Mastering Family Drama in Fiction - BookViral Book Reviews

Here is how to craft family drama storylines that actually hurt (in the best way).

One of the most prominent theories discussed in this field is the Westermarck Effect. Proposed by Edvard Westermarck, this hypothesis suggests that humans have an innate biological "reverse sexual imprinting." Essentially, individuals who grow up in close domestic proximity during the first few years of life—typically siblings—develop a natural sexual desensitization toward one another. This serves as a psychological barrier that reinforces the social taboo. The Alliance Theory