Most individuals have a hard time keeping secrets. But families, for some reason, are fantastic at it.

Contrary to every reality show you’ve ever seen, many families don’t air their dirty laundry, they hide it – affairs, mistakes, addictions, even crimes – both from the outside world, and from other family members.

How do you know if you’re holding onto a piece of the past that is merely nobody else’s business, or if it’s a secret that should be shared with those involved? It’s not as difficult a distinction as you might think, says Dr. Evan Imber-Black, author of The Secret Life of Families: Making Decisions About Secrets.

“Secret matters have shame attached to them. Private matters do not,” says Imber-Black, a marriage and family therapist and director of the Ackerman Institute for the Family in New York City. “The second important distinction is that secrets usually go to the heart of someone else’s right to know the information. It’s about them, or something that affects their well-being, or about their history.”

Take Peter O’Neill, for example. He grew up with a doting, protective mother, never knowing much about his father except that they had divorced when he was 4. That’s virtually all he knew of his dad – until his mother became chatty on her deathbed a few months ago.

“I guess she felt I needed to know everything about my life,” says O’Neill, 68, who listened at her bedside as his 97-year-old mother disclosed secrets about her former husband’s womanizing and drinking. They were stories he had half-assumed but never asked about.

“(My father) had asked her never to tell me about him,” says the grandfather of five. Though he says he wasn’t surprised to hear confirmation of his assumptions about his father, O’Neill was sad to realize that his parents weren’t the happily married couple he thought they were when was born.

Imber-Black is not surprised it took O’Neill’s mother her whole life to come clean.

“Once something becomes a secret, then the decision-making – How do we open it, do we open it, how to deal with the fallout of someone saying ‘Why didn’t you tell me?’ – pulls in the direction of greater secrecy,” she says.

Family members often believe they are keeping a secret to save someone else from the pain of knowing it.

But in most cases, the person being kept out of the loop knows something is amiss, and that can have a devastating effect on the person’s sense of self and security. Dr. Fran Walfish, Beverly Hills child and family psychotherapist and author of The Self-Aware Parent: Resolving Conflict and Building a Better Bond with your Child, recalls meeting with a 5-year-old girl whose parents sent her to therapy because she was so vaguely unhappy. Turns out she and her younger sister had two different fathers, but their mother had married the father of the second child and passed him off as the father of both children.

“This 5-year-old sensed something different in the nature of the way this father related much warmer to his birth child. She felt different and didn’t know why,” Walfish says. “I urged them to tell her the truth, and it really helped her.”

That’s the thing about secrets – chances are they won’t last forever. And getting to pick the way they’re disclosed is crucial.

“Eventually I think most family secrets come out. And when they come out in an unexpected way, without some reasonable control, then I think the potential for bombs dropping, explosions and wreckage and destruction is high,” Walfish says.

If you’re holding onto a secret you think you should tell, the experts have a few tips for how to do it without being shunned for life:

1. Pick your moment.

“Don’t do it at a holiday dinner,” Imber-Black says. “Some people think ‘Oh, I’ve got everybody here,’ but you will be forever the person known for ruining Christmas.” Select a quiet time when no big emotional events are happening in the family’s life – don’t do it near an upcoming birth or wedding, or right after a funeral.

2. Pick your person – one person.  

“Think of who you want to tell. I usually find that telling a secret in a big group is not a good idea,” Imber-Black says. Start with disclosing it to the person most affected by the secret, and then allow that person to decide if and when to widen the circle.

3. Get some support.

If it’s a particularly difficult secret or you think the fallout will be really negative, make an appointment with a family therapist to talk about it first. It doesn’t mean you have to go into long-term therapy, Imber-Black says, but a professional could help you sort through your feelings and put together a healthy action plan for how to tell. It also might help to understand why you kept the secret in the first place. “All of that has to be examined and explored,” Walfish says. “But when it comes down to it, the truth rules.”

4. Be prepared for repercussions.

“If you withheld a secret, the other person has a right to be hurt and angry, and you need to be ready and prepared and sturdy enough to handle it,” Walfish says. “Because from their point of view, withholding the truth is lying.” Steady yourself for the anger that might come, and know that with patience and openness comes healing – in time.

5. Keep the information close.

There’s a difference between disclosing a secret to those who should know it, and blabbing about it on Facebook. “Once a secret is told in a family, then it becomes private,” Imber-Black says.

•July 8, 2014