If you happen to have a physician like Dr. John de Beixedon, you'll find yourself talking about your family history at every physical examination.
"I ask them if anybody new got any diseases this year. And I try and see if there is a link between different family members in terms of cancers," said de Beixedon.
A new study finds that's one of the best ways to track a person's risk for cancer as they age.
"Your family history of cancer doesn't change very much during childhood," said Dr. Sharon Plon, Baylor College of Medicine. "It's really beginning in the 20s when you start to see the curve go up and you really see the most significant changes between the ages of 30 and 50."
That's because our risk for cancer increases as we age, and so does the rest of our family's.
After following 11,000 adults, researchers at Baylor University found at age 30 about 2 percent qualified for early colonoscopy. That means before age 50. At age 50, that number jumped 7 percent, almost tripling just based on family history. At 30, 7 percent of women required a more-intense screening than mammography. By age 50 it was 11 percent.
"What is true at age 30 isn't necessarily true at age 50," said de Beixedon. "Family histories change, personal histories change."
Doctors say besides parents and siblings, you should know about your grandparents, aunts, uncles, cousins and maybe even great-grandparents.
"It's really important to know your whole family history, not just from a cancer perspective, but from a diabetes perspective, from a heart-disease perspective," said de Beixedon.
Researchers also looked at the high risk for prostate cancer in men and found it also doubled from 0.9 percent at age 30 to 2 percent at age 50.
Authors suggest updating your family history with your doctor every five years if possible.