The short answer
Most cancer is not inherited. But a minority runs in families because of a passed-down gene change. A pattern of certain cancers may be a reason to ask about genetic counseling.
Most cancers are not caused by an inherited gene change.
About 5 to 10 percent of cancers are linked to a gene passed down in a family.
Several close relatives with the same or related cancers can be a clue.
Cancer at a young age can also suggest an inherited risk.
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The full explanation.
The short answer
Some cancer runs in families, but most does not. Having a relative with cancer can raise your risk a little, yet the large majority of cancers happen without an inherited cause.
When family history matters more
A smaller share of cancers — often estimated at about 5 to 10 percent — are tied to a gene change passed down through a family. Certain patterns raise the chance that an inherited risk is present: several close relatives with the same or related cancers, cancer appearing at younger-than-usual ages, or particular rare cancers.
Shared genes and shared habits
Families can share more than genes. They often share environments and habits — diet, activity, tobacco or alcohol use — that also affect cancer risk. That is one reason cancer can seem to cluster in a family even when no single inherited gene is involved.
Genetic counseling
If your family history raises questions, a genetic counselor can review it, explain what testing would and would not tell you, and help you decide whether testing is worthwhile. The results may affect screening choices, but the decision to test is a personal one.
Words to know
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Common questions
▸If a parent had cancer, will I get it?
Not necessarily. Having a relative with cancer can raise your risk somewhat, but most cancers are not inherited, and family history is only one of many factors.
▸How much cancer is inherited?
Estimates suggest roughly 5 to 10 percent of cancers are linked to an inherited gene change passed down through a family.
▸What patterns suggest an inherited risk?
Clues include several close relatives with the same or related cancers, cancer at unusually young ages, or certain rare cancers. A genetic counselor can weigh these.
▸What does genetic counseling do?
A genetic counselor reviews your family history, explains what testing can and cannot show, and helps you decide whether genetic testing is right for you.
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