A larger group of women may be at moderately higher risk for familial breast cancer, meaning that breast cancer affects one's relatives across several generations at an above-average rate, but no specific cancer-related genes are involved. The somewhat-higher risk could be related to things that are partially inherited such as body size, a tendency to gain weight during the middle years, or naturally higher level of circulating (endogenous) estrogens. It could also be related to things that are socially inherited, rather than biologically inherited, such as preferences about family size, the proper age for marriage, and even food choices. A woman cannot change her genes, but she may be able to change other factors. For example, many women can control the amount of weight they gain between the ages of 30 and 60 by adopting specific diet and exercise plans. There are aspects of a familial tendency to breast cancer risk that can be changed by individual choices. Again, these choices will help reduce risk, but do not eliminate it.