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Why Do Some Diseases Run in Families?

Updated on: July 2, 2021
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Some diseases are said to run in families, but what does this mean? If your mother, father, or another relative develops a disease, does this guarantee you or your children will also be faced with the same thing?

Why do some diseases run in families and is there anything you can do if you are at risk for something?

Most people consider a disease that affects two more family members within the same biological families something that “runs in families.” There are several reasons why something might run in families, including:

  • Gene mutations
  • Environmental factors
  • Combination of genetic and environmental factors

There are also four different types of genetic disorders including:

  • Single-gene mutation
  • Multiple genes mutations
  • Chromosomal changes, which occurs when entire areas of the chromosome can be missing or misplaced
  • Mitochondrial, which occurs when the maternal genetic material in mitochondria can mutate as well

Ultimately, which of these three issues determines whether or not and how much you have an increased risk for something that affects a relative.

If you have a risk for something due to a gene mutation alone, there isn’t much you can do. Make choices as healthy as possible, but in most cases, it won’t change much. As a matter of fact, you’ll likely know if you’ve inherited the disease before you’re even making choices on your own. However, if you have concerns about a genetic likelihood to inherit a disease, you can also undergo genetic testing. Just do so with the knowledge that you might learn the information you really didn’t want to know.

Some of the most common genetic diseases that aren’t affected by lifestyle include:

  • Cystic Fibrosis
  • Down syndrome
  • Fragile X syndrome
  • Inherited Clotting Problems
  • Familial combined hyperlipidemia and Familial hypercholesterolemia
  • Huntington's disease
  • Duchenne muscular dystrophy
  • Becker muscular dystrophy
  • Sickle Cell Anemia
  • Thalassemias
  • PKU 

Environmental Risks that Run in Families

If your risk is purely environmental, you can make changes that will reduce your risk. You might not eliminate your risk, but you can reduce it a great deal.

In this case, your risk is not genetic. However, the disease might tend to run in your family because more than one person in your family was exposed to an environmental factor.

Why Do Some Diseases Run in Families? 1

For example, if your mother developed lung cancer after smoking cigarettes most of her life, there’s a chance second-hand smoke exposure affected you, giving you an elevated risk for lung cancer. You don’t have a lung cancer gene, but your environment created a higher risk. However, if you choose not to smoke and avoid other things that increase your risk of cancer, you’ll have less of a chance of developing the disease despite your original environmental risk.

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Genetic and Environmental Risks of Disease

Finally, if you have both a genetic and environmental risk for something, you’re in the middle. You can do things to reduce your risk, but you’re still someone with a higher risk for whatever the disease is.

This might sound frightening, but ultimately, knowing your genetic risks and knowing there are choices you can make to reduce those risks is empowering.

Why Do Some Diseases Run in Families? 2

Let’s take a look at a woman who has an increased risk of developing ovarian cancer. Her mother and grandmother both had ovarian cancer, so her risk is significantly higher. She’s aware of this and implements a healthy lifestyle. She eats healthy food, maintains a healthy weight, and stays active. She visits her doctor annually for an examination and undergoes ovarian cancer screenings beginning early in life.

This woman still has an increased risk for ovarian cancer because it’s a disease that runs in her family. But she’s managing the risk as much as possible. And if she develops the disease, doctors will identify it early, making it extremely treatable.

Understanding your genetic risk for medical conditions is a powerful way to manage your health and take control of the situation as much as you possibly can.

There are instances in which lifestyle changes would have little to no effect on someone’s likelihood to have a genetic disease. For example, there is nothing that can be done to reduce someone’s risk of cystic fibrosis. These types of single gene disorders are passed on from parents and recognized early in life. The only thing that can be done is for parents to determine their risk of passing along the risk of the disease to their children and then determining if they want to have biological children due to that risk. Birth defects and genetic diseases are some of the primary reasons people undergo genetic testing. It’s not to determine if they are at risk, it’s to see if they carry a high risk of passing something detrimental along to their potential children.

If you are curious about what diseases run in families and whether or not any of these genetic risks could affect you or your children, you should speak to your doctor. He or she can suggest genetic testing to screen for issues that are of greatest concern. Some at-home testing can also help you identify risks. This is a less expensive place to begin if you aren’t ready to undergo professional testing.

Cheap DNA Kits (all under $60). Read our 2021 Guide.



Genetics Home Reference. “What Does It Mean If a Disorder Seems to Run in My Family?” Genetics Home Reference, 2019,

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