6 Unexpected Health Conditions You Can Inherit

All the more reason to know your family history.

November 14, 2016
Family tree
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You have your dad's hazel eyes, your mom's propensity to tear up at dog food commercials, and your grandma's wit—the apple doesn't fall far from the tree, as they say. 

While most of us can all pinpoint physical features, personality traits, and health history to one family member or another, not everything is set in genetic stone. A little refresher: We inherit two copies of every gene, one from Mom and one from Dad. Sometimes those pairings directly cause an outcome, like your blood type. Other times, environmental factors and lifestyle habits might help tip the scales toward the influence of your genes, making the genetic outcome not quite so obvious, says Lily Servais, senior genetic counselor at the genetic testing company Color Genomics

Here are a few of the more surprising health conditions you can inherit.

The article 6 Unexpected Health Conditions You Can Inherit originally appeared on Prevention.

High cholesterol
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High cholesterol

Typically we blame our diets, but in some cases, high cholesterol is purely genetic, says Shivani Nazareth, a board-certified genetic counselor and director of medical affairs at DNA-screening company Counsyl. "About 1 in 500 people have a genetic mutation that results in a condition called familial hypercholesterolemia and are at risk of premature heart attacks and stroke," she says. The genetic mutation prevents people with familial hypercholesterolemia from metabolizing cholesterol normally, so it builds up in their blood instead. "They could eat a vegan diet and run marathons, but still have higher cholesterol levels because of this inherited trait," Servais says.

Related: Top 10 Cholesterol-Fighting Foods

Pink ribbon for breast cancer
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Breast cancer...from your father

When we think about family history of breast cancer, we usually focus on female relatives. But you can inherit the BRCA1 or BRCA2 mutations, known to increase breast and ovarian cancer risk, from either parent. "Men who have a BRCA1 or BRCA2 mutation may never develop breast cancer because male breast cancer is so rare to begin with," Nazareth says. "However, they can pass the mutation to their daughters, who then have a greatly increased risk above the general population to develop certain cancers." Men who inherit these mutations, Servais says, are also at a higher risk of prostate and pancreatic cancer.

Male pattern baldness
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Male pattern baldness...from your mother

Believe it or not, one particular gene that plays a role in balding is located on the X chromosome, which men inherit from their moms. However, before you go blaming Mom, it's not the only gene involved in the balding process, and environmental factors likely play a role, too, Nazareth says.

Related: Why The Heck Is My Hair Falling Out?

Speech bubble full of question marks
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Conditions never before seen in your family's history

Our risk for many health conditions is calculated by how prevalent that disease is in our family tree. A strong family history of breast cancer, for example, might lead to earlier or more frequent screening, early adoption of preventive lifestyle changes, or even prophylactic surgery. "Family history is a good place to start, but it doesn't always tell the whole story," Nazareth says. Some genetic diseases are much harder to spot. Autosomal recessive diseases are inherited from parents who carry mutated genes but may be healthy themselves; recessive genes get trumped by the dominant genes, but can still be passed on.

In fact, about 80% of children born with a recessive genetic disease have two healthy parents and no family history of that disease, Nazareth says. When both parents are carriers, even if they're healthy, a child has a 25% chance of inheriting both mutated versions and getting sick. Examples range from the relatively benign—like Wilson's disease, which impairs a person's ability to metabolize copper and can usually be effectively treated by reducing copper exposure—to the extremely serious, like spinal muscular atrophy, which eventually stops babies' brains from communicating with their muscles and is the most common genetic cause of infant death, Nazareth says. "We advocate for carrier screening tests so that you have this information in advance of having a baby," she says.

Finger prick for diabetes
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Maturity-onset diabetes of the young

Diabetes, like high cholesterol, is typically determined by a complex combo of genetic and environmental factors, but in as many as 5% of cases, people (typically kids or teens, but sometimes young adults) develop symptoms that look like type 2 diabetes without the obvious risk factors like obesity or inactivity. This so-called maturity-onset diabetes of the young or MODY is actually due to a genetic mutation, Servais says. Without genetic testing, these people are often diagnosed with type 2 diabetes, which might result in them getting less-effective treatment.

Milk
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Lactose intolerance...or perhaps more accurately, tolerance

A genetic condition called congenital lactase deficiency or congenital alactasia causes babies to be lactose intolerant, but it's rare. Yet lactose intolerance is pretty common among adults: About 65% of us experience a reduced ability to digest lactose, the famed sugar in milk. Makes sense, after all: Once we no longer rely on our mothers' milk, we don't really need to be able to eat or drink dairy products. "In the general population, the gene responsible for making lactase, which is needed to break down the sugars in milk, becomes less active with age," Nazareth explains. But some adults keep producing lactase due to a genetic variation that essentially keeps them lactose tolerant.

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