This is a question that many people often ask. Some patients also have the question: if they already have breast cancer, are their sisters or daughters at risk of developing cancer? Recent research has been able to answer these questions: breast cancer is indeed hereditary. But there is no need to panic because the percentage of breast cancers that are truly hereditary is less than 5% of all breast cancers, and that is for white women. There is evidence that in Chinese women, this percentage is even lower. How is breast cancer inherited? This is a more specialized question. Simply put, half of a child’s genetic material comes from the father and half from the mother, and if either parent has a defect in the genetic material, it can be passed on to the child. It is now proven that the occurrence of hereditary breast cancer is associated with these defects in the genetic material, which means that people with defects in the genetic material are prone to breast cancer. Therefore, breast cancer is passed on to the next generation through the transmission of genetic defects. Such genetic defects have been found in white women, and women carrying such defects have a much higher risk of developing breast cancer than the general population. Therefore, testing for these genetic defects in people at high risk for breast cancer is beneficial for early diagnosis and early prevention of breast cancer. However, these data are limited to white women, whose genetic background is completely different from that of Chinese women, so the data from white women cannot be transposed to Chinese women, and so far, similar studies in Chinese women are very few and cannot be answered specifically yet.