There is no such thing as "average" risk. The word "average" is potentially misleading to lay people but we continue to use it. All women are at risk of breast cancer because they are women. 95% of the breast cancers we diagnose have no family histories and are spontaneous genetic mutations.
Women with a first line family history are at exceptional risk. Hardly a week goes by in practice without an amazed cancer diagnosis saying "but I have no family history". Its the "average" risk patients we should be scrutinzing with care because thats where we will find 95% of the cancers.