But, lifestyle does matter
You are what you eat. There may have been a time when this statement was well-meaning, but it has unfortunately now become a saying that is used to body shame women. People say it in the hopes of guilting women into eating foods that are only non-fat and suitable for people who are on wildly restrictive diets. This is an awful precedent that has been set because the saying itself does have validity. The fact of the matter is that when you eat unhealthily then, the chances are you will be unhealthy you put junk in your body then it is going to break down. Maybe not today or even tomorrow. But, it probably is going to happen.
The same goes for DCIS. While your genes and biological makeup do play a role, some things will increase your risk. These come in the form of lifestyle choices. If you drink a lot of alcohol, then your risk is heightened and not just for DCIS, but for other more invasive breast cancers as well. If you are maintaining an unhealthy weight, then your risk increased. The point is that if you are healthy, then you should stay healthy.