Cancer is a complex group of diseases with many possible causes. Some types of cancer run in certain families, but most cancers are not clearly linked to the genes we inherit from our parents.Cigarettes, cigars, and pipe tobacco are made from dried tobacco leaves. Other substances are added for flavor and to make smoking more pleasant. The smoke from these products is a complex mixture of chemicals produced by the burning of tobacco and its additives. Many of these cause cancer, heart and lung diseases. Being overweight or obese can have far-reaching health consequences, including raising your risk for certain types of cancer. Modern life has led many people to eat more unhealthy foods, eat bigger food portions, and be less active. As a result, people are obese or over weight. Some of the same health problems affecting obese adults can also affect obese children. These include heart disease risk factors such as high cholesterol levels and high blood pressure, as well as asthma, type 2 diabetes, muscle and joint problems, and liver disease. Obese children and teens are also at higher risk for social and psychological problems, such as discrimination and poor self-esteem.