Diseases Can Have Various Causes  Many things influence your overall health and likelihood of developing a disease. Sometimes, it's not clear what causes a disease. Many diseases are thought to be caused by a combination of genetic, lifestyle, and environmental factors. The importance of any particular factor varies from person to person. If you have a disease, does that mean your children and grandchildren will get it, too? Not necessarily. They may have a greater chance of developing the disease than someone without a similar family history. But they are not certain to get the disease. (Watch the video to learn more about why family health history is important. To enlarge the video, click the brackets in the lower right-hand corner. To reduce the video, press the Escape (Esc) button on your keyboard.) Health Problems That May Run in Families Common health problems that can run in a family include: - Alzheimer's disease/dementia  - arthritis  - asthma  - blood clots   - cancer  - depression  - diabetes  - heart disease  - high cholesterol  - high blood pressure  - pregnancy losses and birth defects  - stroke. Alzheimer's disease/dementia arthritis asthma blood clots cancer depression diabetes heart disease high cholesterol high blood pressure pregnancy losses and birth defects stroke.  Learn more about the importance of family history in some of these health problems at Diseases, Genetics and Family History.  (Center for Disease Control and Prevention) Heritable Diseases Some diseases are clearly heritable. This means the disease comes from a mutation, or harmful change, in a gene inherited from one or both parents. Genes are small structures in your body's cells that determine how you look and tell your body how to work. Examples of heritable diseases are Huntington's disease, cystic fibrosis, and muscular dystrophy. Learn basic information about chromosomes. Learn basic information about DNA. Role of Lifestyle and Environment Genes are not the only things that cause disease. Lifestyle habits and environment also play a major part in developing disease. Diet, weight, physical activity, tobacco and alcohol use, occupation, and where you live can each increase or decrease disease risk. For example, smoking increases the chance of developing heart disease and cancer. For common diseases like heart disease and cancer, habits like smoking or drinking too much alcohol may be more important in causing disease than genes. Sun exposure is the major known environmental factor associated with the development of skin cancer of all types. However, other environmental and genetic factors can also increase a persons risk. The best defense against skin cancer is to encourage sun-protective behaviors, regular skin examinations, and skin self-awareness in an effort to decrease high-risk behaviors and optimize early detection of problems.  Learn more about the causes and risk factors for skin cancer.  Clues to Your Disease Risk Creating a family health history helps you know about diseases and disease risks. It can also show the way a disease occurs in a family. For example, you may find that a family member had a certain disease at an earlier age than usual (10 to 20 years before most people get it). That can increase other family members' risk. Risk also goes up if a relative has a disease that usually does not affect a certain gender, for example, breast cancer in a man. Certain combinations of diseases within a family -- such as breast and ovarian cancer, or heart disease and diabetes -- also increase the chance of developing those diseases. Some Risk Factors Are Not Apparent Even if they appear healthy, people could be at risk for developing a serious disease that runs in the family. They could have risk factors that they cannot feel, such as high blood pressure. They might not even know the disease runs in their family because they've lost touch with family members with the disease or because other family members with the disease have kept the information private. Another possibility is that family members who might have developed the disease died young in accidents or by other means. They might also be adopted and not share genes with members of their adoptive family. Getting Professional Advice Family members who think they might be at risk for a disease based on their family health history can ask their health care professionals for advice. The professional may order a test to see if the person has the disease or a risk factor for the disease. For instance, a mammogram can detect possible breast cancer, and a colonoscopy can find colon cancer. Many diseases are more treatable if they are caught early. The first step toward better understanding of your family's health is to learn more about the health of close relatives such as parents, brothers and sisters, and children. Creating a family health history is one way to do that.