The short answer
Cancer is a genetic disease, but the gene changes behind it come in two kinds. Inherited changes are present in every cell from birth and can be passed to children. Acquired changes happen during life from chance, aging, or carcinogens, and are not passed on. The vast majority of cancers come from acquired changes; up to 10 percent are linked to inherited ones.
Cancer is caused by changes in genes that control how cells grow.
Inherited (germline) changes are present in every cell from birth and can be passed to children.
Acquired (somatic) changes happen during life and are not passed to children.
Acquired changes cause the vast majority of cancers.
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The simple version
This page explains the two kinds of gene changes behind cancer. It also shows why the difference matters for testing.
Cancer is a genetic disease. It is caused by changes in genes that control how cells grow and multiply. But those changes come in two kinds, and it helps to tell them apart.
- Inherited changes are present in every cell from birth and can be passed to children.
- Acquired changes happen during life and are not passed on.
Most cancers come from acquired changes. A smaller share is linked to inherited ones.
Inherited (germline) changes
An inherited change is also called a germline change. It is passed down from a parent. It was there in the egg or sperm cell, so it ends up in every cell of the body from the start of life.
That is why a person can carry the change without having cancer. It is also why a simple blood or saliva sample can show it. And the change can be passed to children, so it tells you something about the whole family. The National Cancer Institute notes that up to 10 percent of cancers may be caused by inherited changes.
Acquired (somatic) changes
An acquired change is also called a somatic change. It happens during a person's life. It can come from:
- Random errors as cells copy their DNA and divide
- Aging, as changes build up over many years
- Carcinogens in the environment, such as chemicals in tobacco smoke, UV rays from the sun, or certain viruses
These changes are found only in the cells where they happened, such as tumor cells. They are not present in egg or sperm cells. So acquired changes cannot be passed to children. The vast majority of cancers start this way. Changes build up over time until a healthy cell turns into a cancer cell.
Why the difference matters
The two kinds of change are found by different tests that answer different questions:
- To look for an inherited change, a test uses a sample of healthy cells, usually blood or saliva. A result can guide screening and prevention and can matter for blood relatives.
- To find acquired changes in a cancer, a test uses a sample of the tumor itself. A blood or saliva sample usually will not show them. Tumor results can help guide treatment choices.
The samples and goals differ. So knowing which kind of change is in question helps a care team pick the right test.
An important overlap
The line is not always sharp. Sometimes a tumor test picks up a change that a person was actually born with. When that happens, a separate inherited-risk (germline) test can check whether the change was truly inherited. That matters for the person's future risk and for their relatives.
Inheriting a change is not a diagnosis
Inheriting a cancer-related change raises risk but does not guarantee cancer. A person with an inherited change needs fewer additional DNA changes for a cell to turn into cancer. But they may never get those changes, and may never get cancer.
A calm way to think about it
Two people can hear the words "genetic change" and mean very different things. One kind you are born with. The other builds up over a lifetime. Knowing which is which helps make sense of test results, family risk, and treatment options. A doctor or genetic counselor (a health worker trained to explain gene testing) can explain which kind of change applies to your situation and which test, if any, fits.
Common questions
What is the difference between inherited and acquired gene changes?
Inherited changes, also called germline changes, are present in every cell of the body from birth and can be passed from a parent to a child. Acquired changes, also called somatic changes, happen during a person's life and are found only in certain cells; they are not passed to children.
Which kind causes most cancers?
Acquired changes cause the vast majority of cancers. They build up over many years from random errors when cells divide, from aging, and from carcinogens such as tobacco smoke or UV rays. Up to 10 percent of cancers are linked to inherited changes.
Are acquired gene changes passed to children?
No. Acquired changes are not present in egg or sperm cells, so they cannot be passed on. An inherited change can be passed on because it is present in a parent's egg or sperm cell.
Why does the difference matter?
It changes what a test looks for. A blood or saliva test can find an inherited change and can carry information for blood relatives. Testing a sample of the tumor finds acquired changes that can help guide treatment. The two tests answer different questions.
If I inherit a cancer-related change, will I get cancer?
Not necessarily. Inheriting a change raises risk but does not guarantee cancer. People with an inherited change need fewer additional DNA changes to develop cancer, but they may never develop those changes or the disease.
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Last updated: 2026-07-14Next planned review: 2027-07-14
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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