Family secrets can be the juice of your story whether you are a writer of fiction or memoir. Family secrets can mould character, develop plot, or create a crisis in your story. The power of trying to suppress the secret can create a tension any writer would die for. Discovery of the secret can be the climax if you’ve structured your book as a search or a mystery.
Conflicts can arise between those who want to maintain the status quo and those who want to reveal the truth. Characters may pay the price for suppressing the secret and suffer health or mental health problems. Sometimes the whole family pays the price. Dysfunction is rampant. Why do some characters suffer more than others? Is the price greater for those that suppress the secret or those that want to expose it? Is the family motto "if you don’t think about it, it will go away” better than “the truth will set you free”?
The power of a secret is in its repression. When a secret is suppressed, chronic anxiety, family conflict, personality problems or a need for reinvention of the self can result. When the truth is told, your characters can move on and live their lives, free of the powerful force that had been running them. The emotional charge has been lifted. The family can be viewed by a character as if on a stage, and with about as much emotional investment as if a member of the audience.