If one of our parents has Lynch syndrome, at the point of conception, they have a 50% chance of passing on their altered copy and 50% chance of passing on their unaltered copy. If a person inherits the altered copy, they will have Lynch syndrome.
The Lynch syndrome genes are like police officers in our body, checking that cells know when to stop dividing and do not turn into cancer cells, and by doing so they protect us against cancer. If these genes aren’t working properly, this might result in fewer police officers protecting us against cancer.
Lynch Syndrome Ireland 