Oh wow, this question is right in my wheelhouse. I read a lot in this corner of the genre, and it's less about the drunkenness itself and more about what the intoxication unlocks. It becomes this narrative device that shatters the carefully maintained facade of 'normal' family life. The secret isn't usually a single buried fact; it's a whole ecosystem of unspoken rules, simmering resentments, and forbidden attractions that everyone tacitly agrees to ignore. The drunk mom trope acts like a crowbar, prying that lid off.
Think about it. The inhibitions are gone, so things said and done can't be taken back the next morning. That 'oops, I was wasted' excuse hangs over everything, creating this agonizing tension between pretending it didn't happen and knowing it absolutely did. The secret shifts from being something passively hidden to something actively haunting their interactions. I've seen stories where the aftermath—the sober, awkward breakfasts, the forced normalcy—is way more intense than the drunk scene itself. It forces characters to navigate a new, raw truth about their relationships.
A lot of authors use this to explore power dynamics flipping, too. The parental authority figure becomes vulnerable, maybe revealing a neediness or a past trauma that the kid (usually adult kid, but not always) now has to process. Suddenly the caretaker role is reversed. The family secret isn't just mom's hidden desire; it could be her unresolved grief, her dissatisfaction with her life, her own abusive childhood coming back around. The drunkenness just provides the catalyst for that Pandora's box to fly open. It's messy, uncomfortable, and that's kind of the point of the genre.
The exploration often lingers on the guilt and the shame afterward, which I find more psychologically interesting than the actual taboo act. How do you look your mother in the eye after that? How does the family unit either fracture or develop this twisted new intimacy? That's where the real exploration of secrets happens for me, in the silent spaces between the lines of dialogue the next day.