I have lied by omission and I will keep it like this.
Unless you have a genetic mutation that puts you at any risks, you have no idea what that means. First of all, there is this constant mistake about I have the Angelina Jolie gene or I am a BRCA1 carrier. That's rubbish, we all have these genes, they are the good ones, they belong to a group of 65 tumour suppressor genes. It is when we have a mutation or deletion of one of these, that we have a higher risk of cancer. Each of these 65 genes is specific to some body parts or system and they also work together. They protect us against specific cancers. However a mutation doesn't mean you will get cancer, only that your risk is greater, sometimes a lot greater.
Nobody can tell the OP if she should or should not lie. I didn't tell my parents I have the NF1 mutation which puts me at a lifetime risk of cancer of 60%, with a negative prognosis in case of cancer and a general 10-15 years life expectancy reduction. What I have done is drastically investigate the cancer prevention measures for those genetically induced cancers and adopted a plant based anti cancer diet with a focus on low calories, low proteins, high micronutrients , without malnutrition diet.
For some mutations there is the option of preventative surgery, like breast and ovaries. For other mutations, this is not an option. IN my case, in addition to the cancers, we also have benign, yet disfiguring , skin tumours, called neurofibromas.
What benefits would come from telling my parents? and for that poster who suggesting adopting, we are in 2019 and you can have pre-implantation diagnosis, called preimplantation genetic diagnosis (PGD). You can have children safely.
What to do with the information on your diagnosis? First educate yourself to the world of medical publishing, because between research and change in protocols, there is a 10 year gap. Read, not blogs, but medical papers, medical books, attend conferences and symposiums, see where the research is going and what the latest recommendations are in terms of screenings even if not covered by NHS, and change your lifestyle.
There is quite a lot of research on the BRCA 1 lifestyle intervention because for some reasons, 15% of the women with the mutation don't get cancer and the why can help other cancer inducing genetic syndromes.
So depending on which mutated gene you have, there are options for you to reduce your % risk. You have the knowledge, don't sit , use it to your benefit,