Will genetic testing affect my insurance as a pre existing condition?

My mother was diagnosed at 45 years old with breast cancer. After lumpectomy, Chemo and radiation, she survived. A couple of years later her cancer returned and had spread to her liver, lungs and spine. She passed way on 10/02/07.
My doctor advised me not to get the genetic testing for breast cancer because it could be considered a preexisting condition with my insurance. Is that right?