“Mom, I have something to tell you…
I just learned why I got colon cancer and sebaceous carcinoma. I know why you had uterine cancer years ago. And I know what killed your dad at fifty-six. We have something called Lynch Syndrome.”
I had to tell her so that she could protect herself and so that she could inform her siblings that they may have it, too (and may have passed it on to their children).
By the way, informing my own siblings that they, too, might have it (a 50% chance) was a separate and no less heavy conversation.
Alas, the first place my mother’s heart and mind went was to express guilt at “having given me a disease”. Of course, no such thing ever crossed my mind. There’s no reason to feel responsible for something nobody knew anything about until now.
And I assured her that I felt no differently about her than she did about her own father.