From relatively minor maladies like ear infections to serious diseases like diabetes, a surprising number of childhood health problems have a genetic component. "At least 80 percent of medical conditions are inherited to some extent," says Nancy Mendelsohn, M.D., a pediatric geneticist at Children's Hospitals and Clinics of Minnesota, in Minneapolis.
Of course, you can't change your children's genes, but your own health history can motivate you to be extra diligent about screenings and risk-reducing strategies. Here are nine conditions that run in families, along with ways to protect your kids.
Allergies and Asthma
Hereditary Risk: High
Most Vulnerable: Children whose parents or siblings have a history of asthma or any type of allergy--whether to peanut butter, pets, pollen, or dust mites. "If a parent has allergy-triggered asthma, for instance, the child will be more prone to all allergic diseases, but especially to asthma," explains Scott Sicherer, M.D., a pediatric allergist at Mt. Sinai School of Medicine, in New York City. If one parent has suffered from asthma or allergies, a child's risk is between 30 and 50 percent. Both parents? The risk can be as high as 80 percent.
Best Defenses: Breastfeeding has been shown to help prevent both asthma and allergic skin rashes. If allergies run in your family and you don't breastfeed (or if you need to supplement), you may want to use a hypoallergenic infant formula. Doctors recommend that you avoid peanuts (the most dangerous allergenic food) while nursing and even during pregnancy. The American Academy of Pediatrics (AAP) currently advises that children with a family history of allergies shouldn't have dairy products before age 1, eggs before age 2, or peanut butter or seafood before age 3. Reducing exposure to pollen, mold, dust, and pet dander can also help decrease the risk of asthma and nasal allergies. If you do bring a pet into your home, however, it's best to do it when your child is a baby. Studies have found that children exposed to dogs or cats before age 1 may be less likely to develop allergies because their developing immune systems are less likely to learn to attack these allergens. If you suspect that your child has symptoms of asthma--including chronic coughing or wheezing--talk to your pediatrician because early treatment is important.
High Blood Pressure and High Cholesterol
Hereditary Risk: High
Most Vulnerable: Children whose parents have either of these heart-disease risk factors. If one parent has high blood pressure or high cholesterol, a child's risk is about 50 percent. If both parents are affected, the risk goes up to 75 percent. "The genetic impact for these conditions is very strong," says Ronald Bachman, M.D., chief of genetics at Kaiser Permanente Medical Center, in Oakland, California. A child's risk may be particularly high if he has a parent or grandparent who suffered a heart attack or was diagnosed with heart disease before age 55. Studies also show that high blood pressure is most common in African-American and Latino families.
Best Defenses: Get your child screened. While doctors used to think that high blood pressure and high cholesterol only struck adults, they now know the conditions can begin in childhood, increasing the risk of heart disease later in life. The AAP recommends regular blood pressure checks for all kids 3 and older. Children should also have their cholesterol measured by age 5 if a parent has a level of 240 or greater, or if a parent or grandparent has been diagnosed with heart disease. Research suggests that breastfeeding reduces a child's risk of high cholesterol levels. After infancy, be sure that your child eats a balanced diet and exercises every day.
Hereditary Risk: High
Most Vulnerable: While the exact odds are unknown, it's believed that the tendency to have frequent ear infections is 60 to 70 percent genetic, says Richard Rosenfeld, M.D., chief of pediatric otolaryngology at Long Island College Hospital, in Brooklyn, New York. It's likely that parents can pass on a facial shape or eustachian-tube structure that makes their kids prone to middle-ear problems.
Best Defenses: Doctors recommend breastfeeding exclusively for at least three months, keeping your home free from cigarette smoke, limiting daytime pacifier use, getting an annual flu shot, and reducing exposure to viruses by encouraging your child to wash her hands frequently. If you use day care, consider switching to a provider with six or fewer children, recommends Dr. Rosenfeld. Although ear infections are not contagious, the colds that can lead to them are. Fortunately, children usually outgrow ear infections by age 7.
Hereditary Risk: High
Most Vulnerable: Children whose parents are significantly overweight. If one parent is obese, a child's risk of having weight problems is 40 percent, and it's 70 percent if both parents are obese. "In most cases, however, if a child has a healthy diet and gets regular physical activity, he can overcome a genetic susceptibility to being overweight," says Dr. Mendelsohn. Childhood obesity is nothing to take lightly. It can increase the risk of diabetes, early heart disease, asthma, and some cancers.
Best Defenses: Be a good role model; kids learn their eating and exercise habits by watching their parents and siblings. Doctors don't recommend putting children on restrictive low-fat diets, but it's important to limit sugary sodas and snacks, offer a variety of nutrient-rich foods, cut back on television time (no more than two hours per day), and make fitness a family priority. After age 2, your child's body mass index should be calculated by his pediatrician at every checkup so that weight problems can be spotted early.
Hereditary Risk: Medium
Most Vulnerable: Children who have a family history of melanoma, the form of skin cancer that's the least common, but the most deadly. If one parent has had melanoma, a child's risk doubles to 3 percent. If both parents have had it, the risk is about 5 to 8 percent. Risk is even higher if a parent or close relative was diagnosed before age 50. Basal-cell carcinoma, the most common type of skin cancer, is not genetic. However, blonds and redheads with light eyes are at increased risk because they tend to have fair skin without much natural sun protection.
Best Defenses: Protect your child from the sun. "Even though this disease doesn't strike until adulthood, about 80 percent of cancer-causing skin damage happens before age 18," says Dr. Bachman. It's important to apply broad-spectrum sunscreen with an SPF of 15 or higher every time your child goes outside (even on cloudy days)--especially if melanoma runs in your family--and make sure he wears a wide-brimmed hat or visor. A recent study found that kids who wear sunscreen regularly actually develop fewer moles, which can become malignant. It's also wise to follow the shadow rule: If your child's shadow is shorter than he is tall, the sun's rays are too strong and it's time to play in the shade.
Hereditary Risk: Medium to High
Most Vulnerable: It depends on the type. A child whose dad has type 1 (also known as insulin-dependent or juvenile diabetes) has a one in 17 chance of inheriting the disease. But if his mom has type 1--and was under age 25 when he was born--the child's risk is one in 25. If she gave birth after age 25, the child's risk slips down to one in 100. However, if both parents have type 1, the risk can be as high as one in four. Type 2 (the form that's linked to weight) has a stronger genetic component. If one parent has type 2, the child's risk is between one in seven and one in 13, but with two parents, the risk is one in two. A family history of type 2, however, only seems to matter if a child is also overweight, says Dr. Bachman. In fact, the number of kids with type 2 (once called adult-onset diabetes) is now skyrocketing because of the childhood- obesity epidemic. While Caucasians have the highest incidence of type 1 diabetes, type 2 is most common in African Americans and Latinos. Both types increase the risk of heart disease, kidney disease, nerve problems, and impaired vision.
Best Defenses: Some research suggests that breastfeeding and not introducing solids until a baby is 6 months old may slightly reduce the risk of type 1, but preventive strategies have a greater impact on type 2. Make sure your child is physically active and eats a diet rich in fruits, veggies, whole grains, and "good" vegetable oils like olive and canola. Some experts advise limiting refined starches like potatoes and white bread in kids at risk. A blood test to detect type 2 is recommended after age 10 for kids who are overweight or have a family history.
Hereditary Risk: Medium
Most Vulnerable: Kids whose parents had vision problems during childhood. "If both parents wore glasses as kids, a child has more than six times the average risk of being nearsighted," says Stuart Dankner, M.D., a pediatric ophthalmologist in Baltimore. The risk of developing amblyopia ("lazy eye")--a potentially vision-robbing condition that's often treated by patching the good eye--is doubled if a child's parent had it early in life.
Best Defenses: Make sure your child's eyes are screened during infancy. Assessments by a pediatrician are fine for most babies, but an ophthalmologist should examine those with a family history of eye diseases. Early diagnosis of amblyopia is especially important because treatment is most effective when it's started before age 3. General vision screenings should begin during the preschool years.
Originally published in the October 2005 issue of Parents magazine.