How Your Genes Impact Your Risk for Common Health Issues

When you talk to your friends about their health, you’re liable to hear something about how a certain illness or tendency “runs in the family.”

But the full picture can be a little more complicated. For sure, some health problems are greatly influenced by our genes. But some are affected more by the lifestyle choices we make, and still others are completely random. We often adopt the lifestyle habits of our families—the family that Zumbas together stays healthy together!—and whether you realize it or not, your smart habits may be protecting you from certain diseases, regardless of what your genes have to say about it. Of course, the reverse is also true.

That’s why knowing what your genetic predispositions can enable you to be proactive about staying well and reduce your risk of developing certain conditions. Read on to find out what you can do to stay healthy and whether or not you might benefit from meeting with a genetic counselor.

1. Breast cancer

Celebs like Angelina Jolie and Christina Applegate made the BRCA1 and BRCA2 mutations famous. Inherited from your mother or your father, these mutations can bump your chance of developing breast cancer by age 80 to 70%. There is also a random (not inherited) mutation on the PIK3CA gene that some breast cancer patients have.

“We’ve known BRCA for a long time and we understand the cancer risks that go with it,” says Joy Larsen Haidle, M.S., C.G.C., a cancer genetics expert for the National Society of Genetic Counselors. “There are very specific surveillance recommendations and there are very specific risk-reduction options that people can think about.” But that’s not the case with PIK3CA, which may tell us more about how a patient might respond to treatment, rather than her likelihood of getting breast cancer in the first place, says Larsen Haidle. “If I found a mutation in that gene, it may not change immediate medical management from a surveillance or risk-reduction standpoint. However, it may offer useful information for treatment decisions,” she says.

A genetic counselor can also help you put your puzzle pieces together for a full picture of your risk for breast cancer. For instance, says Larsen Haidle, without testing, it may appear that gene mutations related to breast cancer don’t run in your family, because cancer doesn’t run in your family. But it might be that women in your family had hysterectomies for various reasons, which lowered their risk, and they still had the gene. A genetic test can tell you for sure.

2. Autism

Autism is complex, and presents itself in a variety of ways along the autism spectrum. All types of autism are a result of genetic makeup, but the disorder is not always passed down through families, says Wendy Chung, M.D., Ph.D., Kennedy Family Professor of Pediatrics and Medicine and Chief of Clinical Genetics at Columbia University

“Oftentimes, individuals that are at the quote-unquote higher-functioning end of the spectrum will cluster within families more than individuals who might be nonverbal, self-injurious, or have a lot of significant issues,” says Dr. Chung. People with those kinds of challenges seem to appear more sporadically in families, so genetic testing for the disorder isn’t generally recommended. Often, “It was a random, not inherited, new mutation that ended up leading to their autism,” she says.

3. Heart disease

Figuring out if you have a genetic predisposition to cardiovascular disease is a bit tricky, in part because heart disease is a very broad category. Knowing that you have family members who died of heart disease is just the first step to determining the probability of genetic inheritance, says Larsen Haidle. “Is it something with the muscle, something with the rhythm, something with cholesterol in the blood vessels getting clogged, or was it an aneurism?” she asks. Some heart issues have more of a genetic component than others.

The more information about your family history—and your lifestyle—that you can share with a genetic counselor or your physician, the better able they will be able to assess how heart disease might affect you. That’s because you might “inherit” some of your lifestyle habits from your family, along with your genes, says Dr. Chung. Your diet, for instance, which makes a big difference in your heart disease risk, is probably greatly influenced by how you grew up eating, and whether you still eat that way.

“Heart disease is one of those classic ones that you know is both what you do to your body as well as what you were born with in terms of the genes in your body,” says Dr. Chung.

4. Autoimmune diseases

Some conditions have a hereditary genetic link, but only manifest later in life, and then only when a particular event sparks them. For example, in the case of autoimmune conditions, the genes you inherit may prime your immune system to get confused and attack itself if triggered by something in your environment. But it’s not as if your genes are linked to a specific autoimmune disease, says Larsen Haidle. “There are things like type 1 diabetes and autoimmune thyroid disease that can have the same underlying genetic susceptibility, but attacks two different people in two different parts of the body.” The result? You may see autoimmune diseases cluster in families, but they aren’t necessarily clusters of a single disease.

For example, inflammatory bowel disease (IBD), which includes autoimmune conditions like Crohn’s disease and ulcerative colitis, develops later in life, and your DNA plays a role. “There are definitely inherited genetic factors, but it’s not as simple as you got the ulcerative colitis gene from your dad. You’re not born with the condition,” says Dr. Chung. There’s probably something going on with the immune system in your gut that gets activated, leading to someone with a genetic predisposition for IBD to develop it, she says. Behaviors like smoking, eating certain foods, or taking medications; or even stress could trigger it.

Dr. Chung thinks of these combination environmental and genetic conditions like a garden: “The soil might be fertile, then something starts growing as you add water.”

If you’re concerned because a family member has a particular condition, a genetic counselor may not be able to tell you if you or your kids might get the same condition, Dr. Chung says. But they can help you understand how genetics might factor into autoimmune conditions in your family so you can take steps to keep you and your family healthy.

5. Alzheimer’s disease

When it comes to Alzheimer’s disease, Dr. Chung notes that the story is often oversimplified in the media. While certain families exhibit clear hereditary or genetic factors that result in multiple members having Alzheimer’s, that’s not always the case.

Here’s why: For starters, everyone receives a version of the apolipoprotein E (APOE) gene on chromosome 19 from both their mother and their father. One particular variant, APOE ε4, increases your risk of developing Alzheimer’s disease. But even if you have this variant, and your risk is higher because of it, that does not put your risk at 100%. The same goes for the gene variant that increases your risk for early onset Alzheimer’s—it ups your odds, but doesn’t mean the disease is your destiny.

The lifestyle choices you make also have a big effect on your risk, even if you have a certain mutation, says Dr. Chung. Regular mental stimulation (think: crossword puzzles and sudokus) and weekly exercise (like walking and weight lifting) can both help to maintain brain health and reduce Alzheimer’s risk, says Dr. Chung. “Following a heart-healthy diet (such as DASH or the Mediterranean diet) and maintaining social connections can also help keep your brain healthy,” she adds.

Bottom line:
If you’re concerned about a condition that appears to run in your family, a genetic counselor can sift through your family history and help you determine what tests might be worth taking, what actions may reduce your risk, as well as whether your results might help with research that can improve care for future generations. Ultimately, obtaining this info is a very personal decision. “We’re trying to help you feel like you can make a more informed choice and feel more empowered to be an active part of the conversation with your doctors,” says Larsen Haidle.

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