Sometimes, we hear rumors that a family has got cancer one after another, or there are many cancer patients in a family. At this time, some people start to wonder: Is cancer hereditary? Otherwise, how can all the family members have cancer? Is cancer really contagious? According to epidemiological studies on cancer, the phenomenon of “family cancer” has increased significantly in recent years, and they can occur simultaneously or sequentially, and their cancer sites can be the same or different. However, up to now, most scholars believe that cancer cannot be transmitted. A lot of statistics show that doctors and nurses in oncology hospitals who have long-term contact with cancer patients do not have a higher incidence of cancer than the general population. Can cancer be hereditary? After a long period of exploration and research, scientists now agree that cancer is mainly caused by environmental factors, but heredity also plays a role. This is because some people (or some families) have tumor-sensitive genes in their collective cells, which may be passed on to new individuals (children) through the combination of chromosomes in the germ cells of both parents, so that the children will also have such tumor-sensitive genes in their cells. Once the “conditions” are right, these genes are activated and cause uncontrolled cell proliferation, which eventually leads to the development of cancer. Nowadays, it is certain that breast cancer, colon cancer, lung cancer, retinal cell carcinoma (retinoblastoma), leukemia, etc. are tumors with certain genetic predisposition, for example, a woman whose mother or sister has breast cancer has three times higher risk of breast cancer than the average woman. Environmental factors have the greatest influence on the emergence of “family cancer”! Key factors: lifestyle, diet and environment. The scientific explanation for the occurrence of this phenomenon is the shared lifestyle, diet and environment of family members. Since members of the same family eat in the same pot for years, they influence each other and “assimilate” the lifestyle and living habits, and live in the same environment, so they are often influenced by the same pathogenic factors or cancer-causing factors. Therefore, it is not surprising that people suffer from the same type of disease or cancer. According to the available information, “family cancer” is most common in the digestive tract, which also supports the relationship between living habits and living environment and cancer incidence. Research results also show that families with esophageal cancer tend to have low income, low animal protein intake, frequent intake of unfresh food and moldy salted vegetables, hot noodles and strong stimulating foods such as chili peppers. This can easily cause mucosal lesions in the esophagus, leading to esophageal inflammation and gradually developing into esophageal cancer. Another example is bowel cancer, which is also related to low fiber content and high fat diet. In addition, some family cancers are caused by prolonged common exposure to the same germ, for example, H. pylori is the most common bacteria with a 50%-60% infection rate in the population, which may cause gastritis and peptic ulcer and may develop into stomach cancer in the long term. Emotions can also have an impact on this. Emotions among family members are also a triggering factor that cannot be ignored. Lack of harmonious atmosphere in the family, spouses complaining against each other, difficulty in coordinating life with the elderly, and living in long-term tension and anxiety are also predisposing conditions that cannot be ignored in family-type cancer. Psychological negativity, frustration, and negative emotions that ripple through each other and affect the whole family are another major factor in cancer triggering.