It can be hereditary, but it rarely is. Less than 10% of all cancers are and not a single one has strong hereditary component. All blood relatives of a breast cancer patient are not at a higher risk for getting breast cancer, only about 5% of breast cancers are hereditary and about 75% of patents diagnosed with breast cancer have no family history of it. Considering there are hundreds of cancers and 1 out of every 2 men and 1 out of 3 women have a lifetime risk of getting one of them it is not unusual to have multiple family members to have developed it.

There is a body of evidence that suggests that several forms of cancer have a strong hereditary component. If there is breast cancer in your family, for instance, all who are blood relatives of that person are considered to be at higher risk for developing the disease. There are other forms of cancer, though, where there is no evidence of heredity being involved. That may change as study and research into these diseases continues…

Cancer is rarely hereditary; fewer than 10% of all cancer cases are.

An indication that cancer may be hereditary within a family is when several members of the same side of that family have had the same type of cancer, especially if some of them developed it at an unusually young age.

You don't inherit a general tendency to get cancer, and several members of your family having had different types of cancer isn't hereditary and doesn't increase your risk of getting cancer.

Cancer diagnosed after the age of 50 is less likely to be hereditary.

I don't know why, but every time this question is asked on YA somebody claims that breast cancer is particularly hereditary. Not true - only 5 -10% of breast cancer cases are hereditary. I am the only person in my immediate family, and as far as we know my extended family, to have been diagnosed with breast cancer. I have been assured mine is not hereditary and no members of my largely female family are at increased risk of developing it.

Denisedd's (the cancer registrar) answer is absolutely correct.

yes,i've had my mother,uncle and aunt (maternal side) die of it and now my cousin has it.