For starters, you’re missing your father’s 50% contribution to your genetic makeup. And you’re overlooking the role that lifestyle plays. Whether you smoke, eat your fruits and vegetables, exercise regularly, and get screening tests all affect your odds of developing cancer, heart disease, and other health problems. But if you’re worried about your health inheritance, there are a few things you should know and do.

Breast Cancer

Your Risk Having a distant relative, such as a cousin or great-grandmother, with breast cancer slightly increases the average one-in-eight lifetime risk of getting the disease. But having a first-degree relative with breast cancer (your mom, sister, or daughter—or father, brother, or son, since men can also get breast cancer) can double the risk. The risk is even higher if that relative was diagnosed before age 50. And having two first-degree relatives can boost the odds as much as threefold. In some families, the culprit is a mutation or glitch in the genes known as BRCA1 and BRCA2, which you can inherit from your mom or dad and that may also increase your risk of ovarian cancer. Of the 1 in 200 women with a mutation, about 50 to 80% will develop breast cancer. [pagebreak] Improve Your Odds Even if you don’t have a family history, there’s some evidence that staying close to your ideal weight, exercising, eating lots of produce and little fat, and having no more than one alcoholic drink a day may help you avoid breast cancer, says Debbie Saslow, PhD, the ACS’s director of breast and gynecologic cancers. If you have a strong family history of breast cancer (more than one close relative with it), you should also follow this advice:

See a genetic counselor. A counselor can analyze your risk and help you decide whether to get tested for BRCA mutations.Step up the screening tests. In addition to doing a monthly breast self-exam that everyone should start at age 20, ask your doctor about these screening tests, which can help detect cancer early, when it’s most treatable.Clinical breast exam. As often as every 6 months, starting at age 20, for women with known mutations in the BRCA genes or a strong family history.Mammogram. In the event of a strong family history, some experts recommend yearly mammograms 10 years before the youngest age of diagnosis in your family. Many advise women with BRCA mutations to start getting screened between ages 25 and 35.Breast ultrasonography and MRI, which may help detect breast cancer in the denser breasts of younger women.Talk about other options. The drug tamoxifen may lower breast cancer risk by as much as 50 percent in women at high risk. Surgery to remove the breasts can also lower risk substantially, as can surgical removal of the ovaries, but these are more drastic steps.Ask about ductal lavage. This recently approved procedure involves analyzing cells from the breast milk ducts (where more than 90% of breast cancers start) for abnormalities associated with cancer. The results can help women further evaluate their risk and decide whether to use drugs such as tamoxifen, Dr. Saslow explains.

Colon Cancer

Your Risk Susan Gilbert’s mother died of colon cancer at age 51. Gilbert, a motivational speaker and author in San Diego, is now 51 herself. She knows that having a first-degree relative with the disease puts her at a somewhat higher lifetime risk: about 6%. (The average American’s risk is 2%.)  If her mother had been diagnosed before age 45, Gilbert’s risk would have risen to 10%. It’s about 17% for women who have two first-degree relatives with the disease. Women with a family history of ovarian, uterine, or breast cancer are also at higher risk.[pagebreak]Those at very high risk, however, are people with one of two syndromes caused by genetic mutations: familial adenomatous polyposis syndrome (FAP) or hereditary nonpolyposis colon cancer (HNPCC). People with FAP develop hundreds of precancerous polyps or growths in their colons and are virtually guaranteed to get colorectal cancer unless they have their colons removed in early adulthood, explains Durado Brooks, MD, the ACS’s director for colon cancer. Those with HNPCC run a 70 to 80% chance of developing colon cancer. Improve Your Odds Once again, there are things everyone should do to lower his or her risk of colon cancer. “Eating a low-fat, low-meat, high-vegetable diet, getting regular physical activity, and avoiding obesity and cigarettes are all good ideas,” Dr. Brooks says. Gilbert eats a low-fat diet and maintains her lean figure by running (she’s a marathoner). There’s also some evidence that calcium supplements and about 400 micrograms (mcg) of folic acid daily may lower risk. If you’re at increased risk of colon cancer, you should also do the following: 

Find out whether testing is for you. If one relative or more has FAP, consider counseling and genetic testing. You should also consider counseling and testing for the HNPCC mutation if your family includes at least three people with colon cancer (including two first-degree relatives), people from at least two generations with the disease, and at least one person diagnosed before turning 50.Step up screening. Colorectal screening should begin for most people at age 50, but you should start earlier if you meet any of the following criteria.You’re at increased risk. Starting at age 40, or 10 years before the earliest case in your immediate family, get a colonoscopy every 5 to 10 years. Gilbert got her first at age 40 and has had three since.A family history of FAP. Start getting regular endoscopies and colonoscopies at puberty.A family history of HNPCC. Get a colonoscopy starting at age 21, and repeat it every 1 to 2 years until age 40, when you should start getting an annual colonoscopy.Talk to your doctor about celecoxib. In a recent study, people with FAP who took the drug celecoxib developed fewer precancerous colorectal polyps than those not taking the drug. Researchers are trying to determine whether it can lower the risk of other hereditary colon cancers.

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Type 2 Diabetes

Your Risk Connie McDowell, 53, a social worker from Coopersburg, PA, is working hard to not be like her mother, who has type 2 diabetes. “I eat small meals several times a day, and I watch my fat and sugar intake,” she says. She also exercises regularly.  In type 2 diabetes (the most common form), your body stops responding to insulin, the hormone that delivers sugar into cells, and it does not produce enough insulin to overcome this problem. The result: soaring insulin levels. Diabetes can quadruple the risk of heart disease and raise your risk for blindness, kidney failure, and even amputation.If you have a parent or sibling with the disease, your lifetime risk is about 38 percent; if both parents have it, your odds could soar as high as 80 percent. Many genes, singly or in combination, could be at work. “But genes don’t cause diabetes,” says Steven C. Elbein, MD, professor of medicine and program director of the General Clinical Research Center at the University of Arkansas Medical School in Little Rock. “They increase the likelihood you’ll get it. There’s a powerful interplay between lifestyle risk (being overweight, not exercising, carrying excess abdominal fat) and genetic risk.”  Improve Your Odds Despite your family history, you can take simple steps every day that dramatically reduce your risks. These measures can also keep hidden diabetes genes turned off. Here’s what Dr. Elbein suggests: 

Know your numbers. Diabetes and early diabetes (known as impaired fasting glucose) are easy to detect with a simple blood check called a fasting plasma glucose test (performed after an 8- to 12-hour fast). A reading of 109 mg/dl or less is normal; 110 to 125 indicates impaired fasting glucose; 126 or higher is a sign of full-blown diabetes. If results are normal, repeat the test once a year. If you have early diabetes, repeat it every 6 months. If you have full-blown diabetes, discuss testing with your doctor.Drop a few pounds. Among the 3,324 participants in the Diabetes Prevention Program (DPP) study, those who lost just 5 to 7% of their body weight (usually by exercising half an hour a day and eating a healthy diet) reduced their risk of diabetes by 58%.Remake your plate. DPP participants also ate more fruit, veggies, and whole grains, and less fat (less than 30% of daily calories). This strategy not only helps you lose weight, but it may help trim abdominal fat, which is a potent risk for diabetes, Dr. Elbein says.Move it! The DPP study aimed for just 30 minutes of exercise, five times a week, and it got big results. Moderate exercise (walking, biking, playing tennis) is enough to improve your odds, though more is better.

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Heart Disease

Your Risk Her grandmother had a heart attack at age 52. Her own cholesterol levels were so high (600 to 800) that even her doctor said “Wow!” When she learned that her brother’s cholesterol was equally stratospheric, Sue Smith (not her real name), 42, of Moorestown, NJ, realized she shared a dangerous family legacy. Her doctor put her on cholesterol-lowering medication. “It may have saved my life,” she says. “If you have two siblings or other first-degree relatives who had a heart attack by age 55 in men or 65 in women, your risk of an early heart attack is 12 times that of the general population. If you have one relative, your risk is three to four times higher,” explains Paul Hopkins, MD, associate professor of internal medicine at the University of Utah in Salt Lake City and a codirector of the university’s Cardiovascular Genetics Research Clinic. One of the most common genetic defects is familial hypercholesterolemia (FH). The half-million-plus Americans with FH have sky-high levels of total cholesterol (300 to 500), near-normal triglyceride levels, and a family history of early heart attacks: between 40 and 55 for men, 50 and 65 for women. The danger: FH increases heart attack risk 20 to 25 times, and it can lead to heart attack as early as age 20! Another widespread but under-recognized hereditary threat is metabolic syndrome. Also called syndrome X, this lethal, often-inherited combination of abdominal fat (a waist measuring more than 35 inches for women, 40 inches for men), triglycerides higher than 150 mg/dl, low levels of HDLs (less than 50 for women, less than 40 for men), and early (or full-blown) diabetes raises heart attack risk even if total cholesterol is normal. Researchers have identified dozens of genes that may play a role in heart attack, high cholesterol, and high blood pressure. “We believe that even mildly elevated cholesterol can be hereditary,” Dr. Hopkins says. “But in many cases, these genes simply make you more susceptible to cardiovascular problems. If you control your weight, eat healthfully, and exercise, you can minimize your risk.” Improve Your Odds Once you’ve plotted your own family history, these steps can help: 

Share your history with your doctor. If you find evidence of early heart attack, a pattern of high cholesterol and/or high trigylceride levels, or a history of diabetes in your family tree, tell your doctor, recommends Dr. Hopkins. Map out a strategy for regular cholesterol, triglyceride, and blood sugar checks, as well as blood pressure monitoring.Talk drugs if you have FH. Ask your doctor about cholesterol-lowering statins, bile acid sequestrants, and niacin therapy. “Even without other risk factors for heart attacks, and with the best of health habits, heart attacks will almost certainly occur in people with FH if cholesterol levels are not lowered,” Dr. Hopkins says. Lifestyle efforts are usually not enough.

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Live healthy. The same exercise and eating strategies that help reduce diabetes risk can lower heart attack risk as well. If your parents or siblings had heart disease later in life, start with a lifestyle strategy; add medications if your cholesterol or blood pressure readings still need a nudge downward.Aim for these numbers. A panel of top heart experts suggests that you aim for these optimal cholesterol levels if you have a genetic risk for heart disease: LDL less than 100, HDL more than 40, total cholesterol less than 200, and blood pressure less than 140/90 (some evidence suggests that less than 130/85 is more protective).Watch your blood sugar. Even early diabetes (slightly elevated blood sugar) significantly raises heart disease risk. Get checked now, and talk with your doctor about a treatment and testing strategy.

Get Your Genes a Checkup

If you think you may have inherited a flawed gene, most experts recommend that you see a genetic counselor. If nothing more, you’ll gain peace of mind. Here is a step-by-step guide on how to prepare for your visit, as well as what you can expect once you get there: Step 1. List all your relatives. Include four generations: you, your children, your siblings and their children, your parents, both sets of your grandparents, your aunts and uncles, and their children (your cousins). Next to each person, write down how they are related to you and any health information you have about them. For example, if your Uncle Ernie had a stroke, include that next to his name, along with his age at the time he had it. The genetic counselor will probably use this information to create a diagram called a pedigree, which keeps track of who is related to who in a family. Step 2. Record specific medical histories. Try to obtain the following information for each relative on your list, then record it next to their name: date of birth, reproductive history (including number of pregnancies, miscarriages, stillbirths, childhood deaths, mental retardation, and birth defects), age at death and cause of death, and age when any significant medical problems were diagnosed (such as diabetes, cancer, or heart disease). Be specific: For example, record whether the person had cancer in one or two breasts. Also include the number of cancers, original sites of cancers, and whether cancers spread to different locations. Include any histories of precancerous conditions (such as colon polyps) and the age at diagnosis, as well as lifestyle habits that are known to increase risk for health problems and certain cancers, such as smoking and excessive drinking.[pagebreak]   Step 3. Discuss your family history with your doctor. The next time you visit your doctor, show him the information you were able to obtain. He can review the information and may ask you some additional questions about your family history to determine if there are any patterns in your family that could alter his medical recommendations for you. For example, if your mother was diagnosed with breast cancer at age 40, your doctor will probably recommend that you start screenings at age 30 rather than 40 (which is the usual age to start screenings in the general population). Your doctor can also help you decide whether you should seek genetic counseling.A genetic counselor can help you evaluate your risk of cancer, outline the pros and cons of genetic testing, and develop a plan to help you minimize that risk.  To find one in your area, call the National Society of Genetic Counselors at (610) 872-7608 (press 7 for the consumer line). Or vist their Web site at www.nsgc.org. Some, but not all, insurance companies will pay for counseling and testing, so call yours for details. Step 4. Update your family history annually. Now that you’ve got the initial information on your family’s medical history down, it’s important that you keep the data current. Record both the happy events (weddings and births) and the difficult ones (when a relative is diagnosed with a serious illness or passes away). You’ll need medical information on people who marry into your family too. Remember that you’re creating a document that will be valuable not only to you, but to future generations.  “The bottom line is to really try to get a good sense of your family history while your relatives are still living,” says Tiffani DeMarco, a genetic counselor at Georgetown University in Washington, DC. The diseases that killed your family members are the core of what genetic counselors use to determine your likelihood for getting various diseases.