Thanksgiving, when everyone is stuffed to the gills with butter-laden mashed potatoes and struggling to find space for that last forkful of whipped cream-covered pumpkin pie, may not seem like the ideal time to talk about anyone’s diabetes or heart disease. But that’s exactly what federal health officials want you to do.

To encourage people to learn about their families’ medical histories, the U.S. Surgeon General designated Thanksgiving as National Family Health History Day. The hope is that as extended families gather under one roof, they will set aside some time to discuss and record illnesses that might run in the family.

Related: What’s Lurking in Your Family Health History?

If you find out your aunt has Type 2 diabetes, for example, that might be a tipoff for everyone at the table to watch their weight, exercise regularly, consider ditching the junk food and ask their doctor whether they should have a blood sugar test. Or if it comes out that Grandpa Joe in fact had bipolar disorder , that’s something the family should know so they can watch for symptoms in themselves and their children.

Getting the ball rolling

While festive occasions may seem like the wrong time to bring up topics such as Alzheimer’s disease or cancer, talking about health problems comes naturally to some of us, so why not put those inclinations to good use? It’s better than starting an argument about politics or religion.

“It’s always a good time to talk about your family health history,” said Michelle Fox, a genetics counselor in the Los Angeles area and an adjunct associate professor in the department of pediatrics at the University of California at Los Angeles. “What people tend to do is wait until somebody gets very sick, or they wait until there’s a death in the family to talk about it.” The Thanksgiving holiday, she says, “is much better than when you are gathered in the ICU or you are gathered for a funeral.”

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Of course, people are not always open to frank discussions about their medical histories, Fox says. It’s not uncommon for an older person to hide his or her family medical history — such as the real reason grandma was institutionalized — from younger generations.

In other cases, people with a genetically driven disease, such as breast cancer linked to the BRAC1 gene, may feel a moral responsibility to inform relatives who may have the same gene and face an increased risk of that disease.

When and how to start

Wait for the right time to bring up the topic, says Fox. It’s probably better to wait until dinner is finished and people are relaxed and ready to chat, she notes. Remind everyone that the details they share will benefit everyone in the family.

What information should you gather? According to the CDC and the Surgeon General, go back at least three generations and find out the age at which your biological relatives, living or dead, were diagnosed with a particular disease, as well as the cause of death of all your family members who have died and when they died.

To help you capture the data, the Surgeon General developed My Family Health Portrait , a web-based tool you can use to record, share and maintain your family medical history. It takes about 15 to 20 minutes to complete once you have the information you need.

When you’re done, print it out and share it with your doctor, who should review it with you and may recommend screening tests or medication or lifestyle changes. He or she should also incorporate relevant information into your electronic health record.

Daniel S. Levine is an award-winning journalist who heads the Levine Media Group and hosts The Bio Report and RARECast podcasts. He was an editor of The Burrill Report and worked for the Oakland Tribune, Adweek, the San Francisco Business Times and other publications.