A personal decision
Some people only need to consider their own risk when taking a genetic test, but others need to have in mind as well the future of their children and their families.
Knowing your future cancer risk can relieve the weight of uncertainty, allowing you to move forward with your life, even if you carry a mutation.
Even so, you have the right not to want to know, maybe because you think you will not be able to cope with the anxiety about the future.
Nonetheless, taking the test can help you understand your risk, that of your siblings or your children better. It guarantees that the most suited surveillance and prevention options are put in place to manage this risk.
Some people can feel guilty if they are not carriers when their siblings are, or if they have the mutation, about transmitting it to their children.
To be tested carries advantages but also apparent disadvantages, all of which you should discuss and ponder with your doctor. Always keep in mind, though, that knowing the type of mutation causing your family cancer will result in you having better prevention and treatments (e.g., an opportunity to participate in clinical trials targeting your mutation).
Even if you decide against the test, you need to be enrolled in a disease surveillance plan.