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Cancer Awareness GuideGeneral information & support

Is cancer hereditary? Genes, family history and risk

Many people worry about cancer when a parent or other relative has had it. The short answer from leading health authorities: cancer itself is not passed down, but an increased risk of some cancers can be. Here is what that means, in plain language.

For information only - this is not medical advice. If you are concerned about your family history, talk to your doctor, who can refer you for genetic counselling if appropriate.

Cancer is a genetic disease - but usually not inherited

The US National Cancer Institute (NCI) explains that cancer is a genetic disease, meaning it is caused by changes in the genes that control how cells grow and multiply. That is not the same as saying it is inherited. According to NCI, cancer-related gene changes can happen because of (NCI: The Genetics of Cancer):

  • random mistakes in DNA as cells divide;
  • damage from things in the environment, such as chemicals in tobacco smoke, UV rays from the sun and the human papillomavirus (HPV);
  • a gene change inherited from a parent.

NCI states that the vast majority of cancers occur by chance, as gene changes build up in cells over many years. That build-up is also part of why cancer becomes more common with age.

What can be passed down

NCI is clear that cancer itself cannot be passed from parents to children, and that the gene changes inside a tumour are not passed on either. What can be inherited is a gene change that increases the risk of cancer, if it is present in a parent's egg or sperm cells. A well-known example is a harmful change in the BRCA1 or BRCA2 genes, which gives a much higher risk of breast and several other cancers.

NCI estimates that up to 10% of all cancers may be caused by inherited genetic changes. Importantly, inheriting such a change does not mean a person will definitely get cancer - it means their risk is higher than average.

Family cancer syndromes

When an inherited gene change gives family members a higher-than-average risk of certain cancers, it is called a family (or hereditary) cancer syndrome. NCI describes these as rare. One example is familial adenomatous polyposis (FAP), caused by changes in the APC gene, which carries a very high chance of colorectal cancer at an early age.

Why cancer can seem to "run in families" without a faulty gene

Not every family with several cases of cancer has an inherited syndrome. NCI gives several other reasons:

  • Shared environment or habits - for example, smoking or exposure to air pollution in the same household.
  • Chance - common cancers can affect more than one relative simply because they are common.
  • Many small effects - a combination of many gene variants that each raise risk only slightly.

Family patterns worth mentioning to a doctor

NCI lists features that can suggest a hereditary cancer syndrome and may make genetic counselling worthwhile (NCI: Genetic Testing for Inherited Cancer Risk):

  • a relative with a known inherited harmful gene change;
  • cancer diagnosed at a young age, for example colon cancer before age 50;
  • several different types of cancer in the same person;
  • several close relatives (parents, siblings or children) with the same type of cancer, or patterns such as breast and ovarian cancer in the family;
  • cancer in both of a pair of organs, such as both breasts or both kidneys;
  • rare cancers, such as breast cancer in a man.

If any of these apply to your family, it is worth writing down who had which cancer and at roughly what age, and taking that to your doctor.

Genetic testing and counselling

Not everyone needs genetic testing. NCI advises that your doctor can help decide whether testing makes sense, and that genetic counselling is generally recommended before testing. A genetic counsellor can explain the possible benefits, drawbacks and limits of a test, and what results might mean for you and your relatives. Where possible, testing often starts with a family member who has had cancer.

NCI also notes that at-home genetic tests have many drawbacks and are not generally recommended as a way to check for inherited cancer risk. Results can be hard to interpret without professional help, and a negative result does not always mean low risk if your family history is strong.

Genetic testing for inherited risk is different from biomarker testing, which looks at gene changes inside a person's tumour to help guide treatment.

Who may be offered genetic testing

NCI notes that clinical practice guidelines recommend genetic testing for anyone diagnosed with certain cancers, including triple-negative breast cancer, ovarian cancer and pancreatic cancer. Other groups NCI lists include people diagnosed with colorectal cancer before age 50 and people with metastatic prostate cancer. Features such as cancer at a young age, or several cancers in the same person, can also suggest an inherited risk (NCI: Genetic Testing for Inherited Cancer Risk).

Guidelines differ between countries and change over time, so whether testing is offered to you, and how, is a decision for your doctor or a genetics service.

What genetic test results can mean

NCI explains that a test for inherited cancer risk can give several kinds of result:

  • Positive: the laboratory found a genetic change that is associated with an increased cancer risk. It shows a higher risk, not that cancer will happen.
  • Negative: the laboratory did not find any harmful genetic changes. NCI notes that even a true negative result does not mean there is no cancer risk - the person still has the general risk everyone has.
  • Uninformative negative: NCI uses this term when a family has a strong history of cancer but no known harmful change has been found.
  • Variant of uncertain significance (VUS): a genetic change for which there is not enough data to know whether it increases cancer risk or not. NCI notes that most often a VUS is later reclassified as benign.

Because results can be hard to interpret, NCI advises that genetic counselling is generally recommended before testing, so that someone can explain what each possible result would mean for you.

What results can mean for relatives

NCI points out that genetic tests can reveal information not only about the person tested but also about their blood relatives. A positive result may help other family members decide whether they want counselling or testing for the same change. Each relative can choose whether they want to know. In the United States, NCI notes that the Genetic Information Nondiscrimination Act (GINA) prohibits discrimination based on genetic information in health insurance eligibility or rates, but it does not apply to life, disability or long-term care insurance, or to members of the military. Rules differ in other countries.

How to write down your family cancer history

A clear family history helps a doctor decide whether a referral for genetic counselling makes sense. These steps follow the family features NCI lists:

  1. List close relatives first - parents, brothers and sisters, and children - then grandparents, aunts, uncles and cousins on both sides.
  2. For each person who had cancer, note the type and where in the body it started, if known.
  3. Note the age at diagnosis, even roughly. Cancer at a young age is one of the features NCI highlights.
  4. Note if anyone had more than one cancer, or cancer in both of a pair of organs, such as both breasts or both kidneys.
  5. Record any known genetic test results in the family, such as a harmful BRCA1 or BRCA2 change.
  6. Take the list to your doctor and ask whether genetic counselling would be useful. If you are already seeing a specialist, see what is an oncologist? for the roles of the different cancer doctors.

If you do have a higher risk

Knowing about a higher inherited risk can help you and your doctor plan. NCI notes that people at higher risk may be advised to have screening earlier or more often than others - see cancer screening explained. The general steps in reducing cancer risk still matter for everyone. For background on how gene changes lead to cancer, read what is cancer?, and if you are preparing for an appointment, our questions to ask your doctor can help.

A family history of cancer is a reason to have a conversation with your doctor, not a reason to panic. Most cancers are not inherited, and a higher risk is not a diagnosis.

Sources

Published 15 October 2026. Last reviewed: 10 November 2026.

Common questions

Can cancer be passed from parent to child?

Cancer itself cannot be passed down. What can be inherited is a gene change that raises the risk of some cancers, such as a harmful BRCA1 or BRCA2 change.

How many cancers are hereditary?

The US National Cancer Institute estimates that up to 10% of all cancers may be caused by inherited genetic changes. Most cancers happen by chance as gene changes build up over time.

If my parent had cancer, will I get it?

Not necessarily. Most cancers are not inherited, and even an inherited gene change means a higher risk, not a certainty. Tell your doctor about your family history so they can advise you.

Should I take an at-home genetic test?

NCI notes that at-home tests have many drawbacks and are not generally recommended for checking inherited cancer risk. Ask your doctor whether genetic counselling and testing are right for you.

What is a variant of uncertain significance?

NCI describes a variant of uncertain significance (VUS) as a genetic change for which there is not enough data to know whether it raises cancer risk. Most often a VUS is later reclassified as benign.

Does a negative genetic test mean I will not get cancer?

No. NCI explains that even a true negative result does not mean there is no cancer risk. You still have the general risk that everyone has, so keep following screening advice.