For whom?

Genetic testing should be done on anyone suspected to have a genetic mutation linked with the breast cancer of in his or her family.

WHO ARE THEY?

Individuals from families with many cases of the same cancer syndrome, that often appears at very young age.

To belong to one of these families might carry no problem, though, as long as you do not have the diseased mutation. In that case, your risk will be similar to that of the general population.

However, because the risk might be higher for some relatives, these families should always be followed by a doctor/geneticist in a genetic clinic so each case can be individually analyzed and treated. 

The genetic test is done in these specialized clinics if the doctor has strong suspicion of a hereditary cancer.

Testing is not obligatory; this is  a personal decision  and should only be done together with  genetic counseling.