My mother had lobular breast cancer at 54, her mother had pancreatic cancer at 71, and my great aunt had colon cancer at 65. Are these likely genetic?

Not really. There are malignant conditions wherein associations with various groups of tumors exist. This occurs in hereditary forms of breast and colon cancer and in conditions such as the Lynch Syndrome. In your situation the breast Ca is most likely associated with the MMTV virus, the colon cancer with the polyoma virus and pancreas cancer with an undefined oncogenic factor.
Could be. Your family should speak with a genetic counselor.
Potentially. Breast cancer, pancreatic cancer, and colon cancer are three of a number of cancers that may be linked in families to specific genes. However, the vast majority of these three cancers are spontaneous (unrelated to inherited genetic traits). In your case, these are likely spontaneous, given the ages at disease presentation. A genetic counselor can help complete the picture and screen your family.
Genetic. Colon breast prostate cancer close familial genetic links and defined genes. You may want to seek services of genetic counselor. I am not aware of similar link to pancrease (pancrelipase) cancer.